Americans have long been proud of their supermarkets. The first grocer with food in aisles, to be picked up by shoppers rather than kept behind a counter, opened in Memphis, Tennessee, in 1916. In Bentonville, the hometown of Walmart in north-west Arkansas, Americans flock to a bombastic museum celebrating the firm’s founder, Sam Walton, and his commitment to “bringing low prices to underserved rural communities.”
Today Americans spend a smaller share of their income on food to be cooked at home—about 6%—than people in almost any other rich country. Low prices are reflected in low profit margins. At Kroger, America’s second-biggest supermarket chain, the net margin, after taxes, is about 1.2%; at Walmart, the biggest, it is 2.3%.