But I also share the author's frustrations. I've had a number of times where it decides the weight of something is wrong or for some other reason stops functioning until a store employee intervenes. But sometimes there is no store employee there at all, and I'm standing there at the self-checkout with no way to resolve the situation.
In some of those cases, I've just left my groceries there at the machine and walked out the store. I tell myself "That'll show 'em, they'll have to put all that stuff back on the shelf!" But it obviously doesn't show them anything: they never fix the broken parts of the self-checkout and I end up having to return to that supermarket (or another) for the reason that brought me into the store in the first place.