American police are indeed fucking terrified of the general populace, compared to a lot of other places I've been. What's up with that?
Because they're widely and increasingly reviled as a class of people for things that they themselves likely don't even do, and the general populace is unpredictable at the best of times. We also have lots of guns. They also spend most of their time interacting with the worst in society, and it colors their perspective of the whole. It's not surprising in the least that some of them feel like they have targets on their backs.
Its like this in most big nations with a diverse, melting pot society, altough there does seem to be something specially awful in regards to society's relationship with cops in amurica. Its still quite sad and hilarious how many young people forget that cops are just guys with a dangerous job that often makes them a target, and that they have families to take care of, as well. Hell, I've seen kids who have never had actual contact with any policeman and go on making tumblr posts about hating cops. Hating cops in some parts of the US has basically become the new hip and cool thing to do.
Not really?
First of all, cops aren't actually in that much danger in the US as a whole. Looking at the actual statistics there are an average of less
than 3 cop deaths per year per state. Furthermore, less than half of these are violent deaths. No law enforcement agency currently is responsible for tracking police killings, but
wikipedia gives a low ball estimate. Assuming that the highest year is complete accurate for all of them (as a very very vague way to estimate for the aforementioned low-balled-ness), the US police force kills 625 people per year. Most estimates I've heard are a little under twice that, but anyway let's be generous since no one really knows. That means that the average US citizen is over 1000% times more likely to be killed by a police officer than to kill a police officer.
Now, its entirely possible that that just means that the police are simply good at fighting in our gun-and-criminal infested old west of a nation. None of those statistics imply any kind of fault either way, so maybe those were all justified killings in combat. It seems highly unlikely, considering that deaths prior to the 9/11 police militarization craze are
about the same as they were post 9/11. But you know, benefit of the doubt. This is all rendered highly moot by the fact that there have been several high profile cases over the previous few years that have revealed that A US juries and the legal system as a whole will basically never charge cops with on-duty murder and B the police force as a whole goes utterly fucking nuts when any member is under criticism in a way that no other profession including the fucking
army does. The most hilarious recent example of this is the police PR statement low-key implying that officers would shoot up a theater playing Hateful Eight because Tarantino showed up at an anti-police protest. Furthermore, there have been some revelations, most notably in at least one Jon Oliver segment I don't care to dig up, that policemen have "confiscated" millions of dollars of assets from varying US citizens who have not been charged with crimes, mostly due to very liberal anti-drug legislation. So regardless of the actual facts (which STILL contradict your and many other people's narrative about the police) its not surprise that people don't trust them.
This brings me to the my second point. The current anti-police sentiment is a new-ish trend but its coming off of the tail end of an anti-police sentiment generated from the war on drugs. Before that it was the civil rights movement, prohibition and probably a bunch of other things I don't remember. Throughout US history its always been something. People in the US have been hating cops before cops in the modern sense even existed, usually with at least some modicum of justification, to say nothing of the fact that early US law enforcement could be fucking brutal (which can mean very different things at different points in history).
All of this is not even touching the race issues that are endemic to the US as a whole that the police department basically inherited from some nastiness more-or-less originating with the failure of Reconstruction. Which is complicated but very real don't let anyone tell you otherwise.