Uh, so far as I'm aware, all cops do that - pull over "suspicious" vehicles on minor offenses or equipment violations, use that as a wedge to "observe the driver acting nervously" and maybe "detect the odor of marijuana." You get to collect revenue or shoo off "undesirables" at worst, both is even better, and sometimes you get free drugs.
I mean, it's not too much of a stretch to think that supervisors whose departments are getting increased revenue from dodgy traffic stops just might not look real hard at the patrol officers supplying those stops when they're "confiscating narcotics" on the street, or "checking something into evidence" at the station.