In a way, I would argue, there are similarities between religion and capitalism. If you're born into the middle class, everyone is always telling you how wonderful it is to be a police officer, military fighter, etc. You're told it's honorable, you're helping society, you make it so people live happily, and so on. This may not be the case, but it's what you truly believe. So I argue that there are some cops who join in an effort to do good - they fail, of course, but that doesn't mean we should fucking kill them.
Of course, if someone attacks you, you should fight back.
I know some people who are police officers personally. I really don't like them, they're assholes. But when I think about them being shot in the street...it upsets me. And it makes me mad that this forum cheers these deaths.