I think it's a combination of a few things: 1) Institutional and culture view of policing, vs say other western countries that are more community policing base

I think it's a combination of a few things: 1) Institutional and culture view of policing, vs say other western countries that are more community policing based. 2) General brotherhood of law enforcement and protecting each other. There is a lack of holding each other accountable. 3) General protection afforded by law, either explicitly or implicitly via half hearted attempts at prosecution / investigation etc. These combined gives law enforcement as an organization and individuals a sense of normalcy in what they do, and also feeling of invulnerability. This doesn't apply to all police officers of course, and I actually believe the majority are law bidding and trying to do good in a tough environment. There are probably also a non trivial amount that gets into law enforcement to wield power over others. Law enforcement needs to be held to a higher standard, and because of the power they wield must be scrutinized much more closely.