[runeks]

> author also use gross profit of Walmart, which sells everything from salt to guns, as a measure of profitability for “grocery” stores.

The article has an entire paragraph dedicated to this:

> Walmart’s shops are enormous, selling plenty besides groceries. Tesco operates over 4,000 shops, the bulk of which are its smallest. Walmart has only 4,700 shops in total, despite serving a population about five times larger. On average, its supermarkets are ten times larger by floor space than Tesco’s. Bigger stores increase consumer choice. A Walmart supercentre might stock 140,000 different items, compared with just 40,000 at Tesco’s biggest branches. But it also means they may be wasting a lot of space by stocking products that do not sell, adding to costs. American supermarkets sell far less per square foot of shop space than British supermarkets, notes Bryan Roberts, a consultant based in London.