For most of human history, buying food was a transaction between two people who could see each other. You knew the butcher. The butcher knew you. He knew what you'd bought last week, what you'd liked, what you could afford, and what was worth recommending today.
The greengrocer would tell you the tomatoes weren't worth it this week; come back in a month. The baker's bread was different from the baker's two streets over, because everything was different from everything two streets over. You gave money. You received food, judgment, and a relationship. The exchange was transparent, mutual, and roughly fair. None of this was efficient. All of it has been replaced.
Every price tag you have ever looked at is the product of a moral argument that most people have never heard of. Before the 1870s, there was no such thing as a fixed price. You walked into a shop and haggled. The wealthy paid less because they had leverage. The naive paid more because they didn't. The vulnerable paid the most because they had no choice. In the mid-nineteenth century, the Quakers decided this was fundamentally dishonest. They believed that charging different people different prices for the same thing was immoral, and they began marking goods with a single, non-negotiable price.
Roland Macy, a Quaker, built his department store on the principle. John Wanamaker institutionalised it in Philadelphia. By the early twentieth century, fixed pricing had spread across Western commerce. One price. For everyone. Regardless of who you are, how much you earn, or how desperate you look. That principle held, unchallenged, for a hundred and fifty years.
Roland Macy and the first Macy’s fixed price store
Britain had roughly 50 supermarkets in 1950. By the end of the 1960s, there were over 3,000. The government actively encouraged the transition to self-service; customers selecting their own items from shelves rather than being served by a shopkeeper behind a counter was more efficient, required less labour, and lowered the cost of feeding the country. In 1957, British households spent roughly a third of their income on food. Today, that figure is about 11%. By almost any measurable economic standard, the supermarket revolution was genuine progress.
The cost of that revolution, however, is harder to quantify, which is partly why nobody has bothered. A chicken in Aberdeen became the same as a chicken in Totnes. Strawberries appeared in December, which is completely insane, but everybody got used to it so quickly that questioning it now marks you as eccentric. Regional variation in food was flattened by centralised supply chains.
Take the market town of Shepton Mallet in Somerset, for example. It had a vibrant collection of independent businesses before the superstore arrived. The town's handsome Georgian architecture remains. The life behind it has largely drained away. Twenty quid spent at a local butcher's circulates through the local economy. £20 spent at Tesco gets extracted to a centralised corporate structure. Both provide food. Only one feeds the town.
Shepton Mallet High Street
Everyone participates in the economy as both consumers and producers. The boundary between those roles has always been yours to maintain.
The supermarket model solved a genuine national problem. It also created a structural one: the economics of selling cheap food to a country that expects cheap food are almost impossibly thin. Full-service grocery retailing operates on net margins of 3-5%. Food and labour each consume roughly a third of revenue. Rent and overheads take most of what remains. Tesco turned over nearly £70 billion last year on a profit of £2.7 billion; a margin so slim that a few bad weeks in any direction can turn profit into loss.
The supermarket model is a treadmill: you win by being the cheapest, but being the cheapest means your margins are the thinnest, which means you need more volume, which means more stores, more overhead, more pressure on the same tiny margin. The economics of food retail, as a standalone business, are structurally incapable of generating returns that justify the scale of capital deployed.
Unless, of course, you find something else to sell.
In 1993, Tesco's marketing team began investigating loyalty cards. The concept was new in British retail, and Sainsbury's had no equivalent. In 1994, a Tesco executive, Grant Harrison, attended a conference where a mathematician, Clive Humby, was speaking. Humby and his wife, Edwina Dunn, had founded a company imaginatively called dunnhumby in their kitchen in Chiswick five years earlier. Tesco commissioned a trial across fourteen stores. After three months, dunnhumby presented its findings to the board. The first response came from Tesco's chairman, Lord MacLaurin: "What scares me about this is that you know more about my customers after three months than I know after thirty years."
Clive Humby and Edwina Dunn
The Clubcard launched in 1995. It looked like a loyalty card. Small discounts in exchange for scanning a piece of plastic at the till. That little piece of plastic was the single most sophisticated consumer data collection operation in British commercial history. Within a year, Tesco overtook Sainsbury's. Within three years, Clubcard had helped double its market share. dunnhumby now holds behavioural data on nearly one billion consumers worldwide. Revenue of £362 million on net margins of roughly 9%, with the retail media business it powers for Tesco generating hundreds of millions on top.
Tesco eventually acquired dunnhumby outright, and in 2015 tried to sell it for approximately £2 billion. They couldn't get the price they wanted, which tells you exactly how valuable they considered it. There are currently 24 million Clubcard households in the United Kingdom. In a country of approximately 55 million adults, which covers virtually every household in the land. dunnhumby sells its behavioural data to Coca-Cola, Procter & Gamble, Unilever, and over 450 other brands through its platform, Tesco Media and Insight. The return on advertising spend (ROAS) on Tesco's platform is £6.60 per pound invested, compared to £3.80 on other channels. Grocery margins: 3 to 4%. The data business operates in a different economic universe entirely.
What is frighteningly clear is that the most valuable product in the store is walking around with a trolley.
You enter a supermarket as a consumer. You leave having been made, without your knowledge or meaningful consent, into a producer. Your weekly shop is an act of production. dunnhumby packages your output and sells it to the brands on the shelves. You receive, in exchange, Clubcard points worth a fraction of a penny per data point generated. You use the card because why wouldn't you? You'd feel like a tin-hat conspiracy theorist for refusing.
But your identity, your habits, your routines, the patterns that make you specifically you, are being put to work generating value for a company whose real customers are Coca-Cola and Procter & Gamble. Social media established that when the product is free, you are the product. Tesco demonstrates that the same principle applies when the product is not free. You are paying for groceries and simultaneously being sold to the people who make them. The boundary between consumer and producer dissolved without anyone asking for your permission.
Which brings us to our brave new world.
Tesco is currently trialling something called "Your Clubcard Prices." AI analyses your individual purchase history and sets a price for you personally. Updated every Wednesday via the app. Valid for seven days. Different prices for different people for the same product in the same store on the same day. Tesco has embedded Adobe's AI engineers directly into its personalisation teams to accelerate the programme across all 24 million households.
One hundred and fifty years ago, the Quakers looked at a commercial landscape where the powerful paid less and the vulnerable paid more, and they called it what it was: morally indefensible. The fixed price tag was their answer. One price, for everyone, as a matter of principle. It became the bedrock of modern commerce. The economics of modern food retail have now led, by a chain of perfectly rational decisions, to the precise moral condition the Quakers set out to abolish.
Tesco sells battery-farmed chicken produced under conditions engineered to extract the maximum yield for the minimum input the animal will tolerate. The personalised pricing algorithm applies the same logic to the customer. It calculates your price sensitivity, determines the minimum discount required to retain your loyalty, and sets the price accordingly. The economics that produce the chicken on the shelf are now being applied to the person buying it.
The people with smartphones, apps, and digital fluency receive the savings. The people without, disproportionately older, less affluent, and less technologically confident, pay the sticker price. The Quakers introduced fixed pricing to protect the vulnerable from the shrewd. Personalised pricing penalises precisely the people the Quakers were trying to defend, funded by their own inability to participate in a system designed around data surrender.
From Tesco's perspective, every step of this was irrefutably rational, logical, and arguably defensible. The margins on food are structurally inadequate; the escape route through data was an economic necessity. Personalised pricing was the inevitable next step: it captures a greater margin and generates richer behavioural data from every transaction. The question is whether the architecture is stable.
Two pressures suggest it may not be. The first is trust: the opacity that makes personalised pricing functional is the same quality that makes it explosive. The first viral social media post comparing two people's Clubcard receipts for the same basket will do more reputational damage than a decade of price competition. The visceral response to this week's Gist video on the same subject suggests the nerve is already exposed. The second is regulation: the EU is already examining algorithmic pricing under its AI Act framework. If personalised pricing is classified as discriminatory, which is not unreasonable given its disproportionate impact on the elderly and the poor, the model faces an existential legal challenge.
There is an alternative, and Britain already invented it. Imagine Tesco said: Your data is worth a specific, quantifiable amount to us. Here is what we sell it for. Here is your proportional share. Not a coupon. An honest dividend. In 1844, the Rochdale Pioneers established the Co-operative on precisely this principle: a business owned by its customers, with profits returned to each member in proportion to their spending. The "divi" was a transparent share of the value your customer generated. The model was invented in Lancashire, two centuries ago, for exactly this kind of problem.
The genius of the current arrangement, of course, is that none of it is visible from the shop floor. You scan your Clubcard without thinking. You tap your card. You load the bags into the car. Forty minutes, start to finish. Nothing about the experience suggests that anything has been taken from you beyond the number on the receipt. You don't feel like a product. You don't feel like a producer. You just feel like someone who bought some food. That is, of course, exactly how it is supposed to feel.
You walked into a shop to buy a loaf of bread. By the time you leave, you have produced more value for the people watching you than the bread costs to make.
You just didn't know you were working.
See you on the next one.
