> Aren't most shoplifters not even caught?
Maybe? I would tend to believe that but it seems impossible to know. I think companies tend to argue something like shrinkage == theft and theft > arrests, but that's pretty suspect since there are many other ways that inventory goes missing.
As to your other point, I think it's a myth that people lose faith in governmental administration and fail to report crime in this context. Maybe that happens with things like sexual violence, but not here where property owners have every economic reason to report theft without considering police availability or effectiveness.
I agree that police don't investigate crime like this (in cities), but in the corporate context they don't need to. This field is dominated by private investigation and security. People are detained with dubious legality by the "loss prevention" employee until police show up, then the store hands over 4k video of the person stuffing baby formula in their pants and walking out of the store.