Wrong kind of crime. That kind of crime doesn't create an income source. It just creates costs. (Jailed person, legal fees, and as you said bas optics).

The crime they do want to catch is the lazy easy stuff. Speeding, bad driving, indecent exposure, antisocial behaviour, anything that can be caught on camera. Doesn't need large legal fees (open and shut cases), causes large fines. Doesn't need investigation.