I think that's really an implementation issue, rather then a problem with the idea. The current batch of self-checkout systems are very very fragile. It seems

I think that's really an implementation issue, rather then a problem with the idea. The current batch of self-checkout systems are very very fragile. It seems that instead of optimizing them for throughput/efficiency, they optimized them for detecting if you are trying to steal something. For example, something as simple as brushing the weight sensor will trigger an alert that takes 15-20s to go away. There's really no reason to do that unless you are worried about people stealing. In reality, checking the weight is a very poor way of detecting this (every system I've seen has an "I'm using my own bag" option that makes the alert go away. These are actually very unoptimized from the UI point of view too. For example, most of the people have their own loyalty card they scan at the beginning. Why not track these, and adjust settings on the machine based on it? For example, I mute the volume whenever I start, that would be nice to keep track of. Defaulting to showing me a list food that I've purchased over my last few trips would make things go quicker instead of me having to dig through pages of items looking for common things.