don’t get paid enough to even look up or deviate from their programming

Also, it's literally not their responsibility to do anything about shoplifting attempts. Normally there is a security person (yes, one) employed in the store, but I wonder if they are only there to tackle aggressive behaviour or to actually peek into people's bags and pockets. As a till worker, you can point out that those things are actually from the store, but I think it's not legal to require you to enforce anything - especially because it isn't (and shouldn't be) in your job description.

Yes, sometimes, it's IDGAF, sometimes it's lack of critical thinking, but more often than not it's "everyone knows but obviously it's out of our scope to make a scene for a jar of gherkins or a cheese wheel". Nobody will think much about it if you actually look like you need stuff, but based on my several years of experience, in the majority of the cases the employees clearly know when someone is trying to do petty tricks, they definitely judge you for that (unless you're in need of course, but you can still ask and get stuff), the employees just won't act for the above 3 reasons.

Isn't it normal to reuse bags from other shops?