It's even more retarded than that. A large chunk of crimes are committed by a relatively small handful of very prolific serial offenders. Catching and jailing the people committing the bike thefts would almost certainly also cause a drop in all those "more serious crimes" they claim to be patrolling for. Even if you took their workload excuse at face value, they'd still be using the workload as an excuse to not do things that would decrease the workload.