Pay on our civil service scale is pretty commonly known. If I know how long a fellow detective is on the job and in rank, I can pretty easily tell how much he makes. That is of course adjusted by the amount of overtime he works. The overtime does sort of function as merit pay. The job does often come up with plans to reduce overtime, but it remains true that the more active a cop is, the more overtime he is bound to earn.
Detectives come in three grades.
I am a third-grade detective, which is lowest. Good detective work and popularity with one's bosses will get one promoted. Good political connections don't hurt, either. In a way, this is a little similar to your hard-core code writers who never want to be managers. There are first-grade detectives in my office who work only homicides, who earn more than the lieutenant who commands our squad, and who wouldn't want to be anywhere else in the hierarchy.