Regarding supermarkets, all the anthropology, all the focus, all the Underhill, is always on the customer or the seller. No story has been written on the checkout operator. Until now:
[T]he checkout might look like the last survival of the old scene in the shop: there is a counter and on the other side of it a human being. But this formal resemblance conceals the great difference. The cashier, unlike the shop assistant, has no role to play in the customer’s choice of what to buy, no words to say beyond formulaic instructions and questions; the job is just to get the given things scanned and paid for. Apart from speed, the only possible achievement is negative, not to have made a mistake.
Success defined in the negative.