I agree with Farhad Manjoo’s assessment in this piece for Wall Street Journal: humans are much better at checking you out at the grocery store than machines. He explains:
They [self-checkout machines] work well enough in a pinch—when you want to check out just a handful of items, when you don’t have much produce, when you aren’t loaded down with coupons. But for any standard order, they’re a big pain. Perversely, then, self-checkout machines’ shortcomings are their best feature: because they’re useless for most orders, their lines are shorter, making the machines seem faster than humans.
In most instances where I’m presented with a machine instead of a human, I rejoice. I prefer an ATM to a flesh-and-blood banker, and I find airport check-in machines more efficient than the unsmiling guy at the desk. But both these tasks—along with more routine computerized skills like robotic assembly lines—share a common feature: They’re very narrow, specific, repeatable problems, ones that require little physical labor and not much cognitive flexibility.
At my local Kroger, the few times I have tried using those self-checkout machines have been full of frustration. For instance, one time an item I scanned went through twice, and there was no easy way to select “duplicate scan” on the screen. Cycling among various on-screen buttons for fresh fruit/vegetable selection is a chore. Until a system is built which recognizes the items you’ve placed onto the scanner without human intervention comes along, cashiers will trump self-checkout computers any day. Imagine how complicated it still is if you have in-store and/or newspaper coupons, checking out via a combination credit card/cash, and so on…