Actually, having a grandfather who was a policeman really brings ACAB home.
My grandpa was pretty open minded and compassionate. I’m sure he was one of the “good ones” but I know what the NYPD is like now and (oddly as a jazz fan) about some terrible things the NYPD did then. If one good cop in Brooklyn can’t affect (probably didn’t know about) police in Manhattan, then a similar great guy can’t really change things much now. Assuming there are “good ones” out there they’ll need outside help.