Police provide a valuable service society. They can provide that service and still not be held properly accountable. The two are not a contradiction. If I was in Russia or China or Egypt, and a crime happened, I would be happy if one of their LEOs showed up to help. It doesn't mean that they are not horribly corrupt police forces.

The infuriating thing that people see is when a LEO with dozens of complaints and a couple of civil lawsuits (paid out by the town/state) finally gets caught absolutely on fire red handed, and maybe gets drummed out, but almost never prosecuted. You have to wonder how someone can so flagrantly violate the law so often without any fellow cop catching them, reporting them, and prosecution happening. You have to wonder why it takes them getting caught absolutely red handed, on video, for action to happen, and you have to wonder why the action finally taken didn't include some quality time inside of a prison cell.

It reeks of institutional corruption from the cop on the beat to DA's office. Normal citizens live by one set of laws, and LEOs live by another. Americans are justice loving folks. There are not many places in the world where someone will obey a red light at a cross roads when no one is coming (not that all Americans do that). LEOs are in large part seen as heroic folks who get praise for upholding justice because Americans tend to be justice loving folks. To see LEOs appear to live by an entirely different justice system that rarely reacts to abuse of power, and when it does react, rarely reacts with criminal prosecution even when a crime has blatantly been committed, drives Americans nuts, as it should. The futility if changing that sort of institutional corruption leaves people more than a little cranky.