Nothing, the same as current self-checkout systems. You can already easily just put stuff in your pocket or ring expensive items up as incorrect, cheaper things. I suspect shops have done a risk analysis and decided that they'd prefer to have more shoplifting and fewer staff.
At least in Walmart I've had workers come over to me multiple times to verify I correctly scanned things. There's definitely more scrutiny involved when you have a centralized self-checkout (this only happens in the more sketchy Walmart, the nicer one seems to trust people more).
> You can already easily just put stuff in your pocket or ring expensive items up as incorrect, cheaper things
This is actually already somewhat solved. The other day I was at a Safeway and one carton of milk had an unreadable label so I scanned a different carton and put the unreadable one in the bag instead (same product). The system showed me a video of me doing that, highlighting the fact that I didn't put the item I scanned on the bag (!) and asked me to wait for an assistant. Pretty impressive.
I doubt the relationship between the rate of shoplifting and ease of shoplifting is anywhere close to linear. Even before self-checkouts existed, people still shoplifted. And in some places, the honor system even works much of the time.
> I doubt the relationship between the rate of shoplifting and ease of shoplifting is anywhere close to linear.
I'm sure you're right. I suspect that there are massive variations from shop location to shop location, even within a region. I also suspect there are different kinds of shoplifting. I remember hearing a friend who is not the kind of person to just pocket an item and leave, bragging about ringing up protein powder from a bulk dispenser as flour to save money. That kind of behaviour is definitely going to be hard to model.