Remember that rogue cop a few years back that killed a few other cops and tried to flee the country?
In their efforts to find them, eight cops open fired on a truck with two women inside. Over 100 rounds fired, and the women thankfully survived despite multiple gunshot wounds. And of course millions of dollars were awarded to those women and none of the officers were fired as a result.
And remember how that situation ended? The cop killer holed up in a cabin in the woods by himself surrounded by hundreds of cops. They decided to burn the place down with the cop killer in it.
Only a few cops are actively over-aggressive and hot headed, but that nearly every other cop stands by as they let the suspect burn alive (or over a hundred rounds fired at a truck without any probable cause) says all that needs to be said.