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.
