You're right though, being a police officer comes with an expectation that doesn't match your pay. If you're on the subway, there is a police officer in uniform standing nearby, and a guy attacks you, the expectation is that the cop would save you. However, in 2011 Maksin Gelman had a stabbing spree in NYC that culminated in an attack on Joseph Lozito. The attack occurred on a subway, with Lozito being stabbed in the head and face while police watched from the conductor's booth. It wasn't until Lozito had wrestled his assailant to the ground and detained him that the police helped him.

Lozito sued the NYPD for not helping him and the judge decided that it wasn't the police's duty to save his life. On the day of the assault the police didn't even perform first aid on Lozito, it was another subway goer that save his life.

EDIT: I'll be the first one to say fuck the police, but if you want actually good police then the first step is to pay them to match what you expect of them or else you'll end up with a bunch of gun toting assholes who won't do shit.