During my adolescence, in a medium-sized fairly poor suburb of Houston, I probably ran into cops drunk, sometimes with weed on me, while underage, at least half a dozen times and never went to jail. It was always a call to my parents. I remember once they didn't even call parents. Cops broke up a party once and allowed us to call sober people to take us home. Maybe its just our town, but the cops seem to have better priorities. I can tell stories for hours of buddies who had a sack thrown away rather than being arrested.
Obviously police are in a position to abuse power, and unfortunately in today's society the vast majority of them do, worse yet they get protected from justice by the system and their buddies, but that doesn't mean it isn't possible for their to be good cops. Speaking in such absolutes is quite frankly ignorant.