the rub: police unions are highly political machines and heavily involved in electing rubber-stamp politicians. it's a quid-pro-quo relationship that we seem to have a very hard time breaking out of in the united states.
re: police requiring unions: i have to disagree with you. american policing originated from two antilabor arms: slavecatchers and union-busters. they wield power over non-police union labor and implement it on every level from the individual to the systemic. they are class traitors by choice and by definition and do not deserve protection, because they are the physical arm of the body we require protection from.