Japan has an insanely high conviction rate. And the cops also don’t bother filing a case unless they’re pretty sure it’s a spam (e: lol) slam dunk

Tokyo Vice, while a drama, actually portrays Japanese police work in a roughly accurate sense. And the whole bit with how the yakuza have their tentacles into EVERYTHING is closer to the truth than many would like to believe.

"Sprinkle some crack on the body and arrest the nearest homeless person, I've got my eye on a new camaro"

No because they don't even bother with any case that can't be cleared pretty much immediately, even if that means declaring obvious cases of murder as suicides or accidents. In criminal investigations accuracy is the most important metric not speed or even severity of the crime. You could pay based on conviction rates of course, but whether a conviction happens or not is often more about how stupid the criminal or prosecutor is, and would potentially incentivise faking evidence which is already a problem.