When people arrive back to where they locked their bicycle and find it vandalised, they often just abandon them forever, so you find bike racks with a certain percentage of rusting, ruined bikes.
Fair enough but... why do they leave them locked there, if they're never coming back? The locks are sometimes more expensive than the bike (or at least a new wheel). Why not take the lock home? Then a) people can recycle the bike if they want, b) people can use that parking slot and c) the victim at least doesn't have to buy a new lock for €€€ in future!