People buy Rolex watches for reasons other than their timekeeping excellence, just as people buy Ferraris and horses for reasons other than going to the store to pick up a gallon of milk and a loaf of bread. Economists talk about “Veblen goods,” which are more valued because of their high prices rather than in spite of them, coveted not for their conventional utility but for their exclusivity. Owning a Rolls-Royce isn’t about the car — it’s about you. Which is why you see magazines such as The Robb Report — one of those glossies full of “bland advertisements for being wealthy,” as the novelist William Gibson put it — for sale in places such as Wal-Mart, where the typical customer is not actually in the market for a yacht or Kiton overcoat. If you’ve ever seen the heartbreaking sight of a young woman stopping a Wal-Mart checker three-fourths of the way through ringing up her purchases — because she does not have enough money to pay for what’s left in her cart — then you can be pretty sure that what’s going in her sack is more or less the opposite of Veblen goods.

Ironically, the anti-Wal-Mart crusaders want to make life worse for people who are literally counting pennies as they shop for necessities. Study after study has shown that Wal-Mart has meaningfully reduced prices: 3.1 percent overall, by one estimate — with a whopping 9.1 percent cut to the price of groceries. That comes to about $2,300 a year per household, savings that accrue overwhelmingly to people of modest incomes, not to celebrity activists and Ivy League social-justice crusaders.

Ultimately, these campaigns are exercises in tribal affiliation.