* Completely unrelated problem, nobody actually knows all the laws.
That's a major problem with the US legal system. There are so many laws on the books that even when they spent millions of dollars and many months trying to catalogue and count Federal laws, they couldn't count them all.
That's very dangerous for a supposedly free and open society. It allows police to arrest anyone as it's almost certain that some law can be found to have been broken. Often police outright ignore the laws, like the right of people to audio-record/photograph/video-record police. Most departments have informed their officers that being video or audio recorded and/or photographed is not against the law but they still arrest people, harass/bully them, and even assault them and destroy recording equipment on a regular basis and receive little or no meaningful consequences for their crimes.
The other fairly recent phenomenon that drives distrust and hatred of police is this priority of "going home tonight" above anything else. It leads officers to shoot first and ask questions later because "officer safety" is priority #1.
The job of police is to protect and serve. They cannot do either if they put their safety above anything else including innocent lives. It turns any encounter with police into a potentially deadly (for the citizen) situation. It changes police into a paramilitary occupation and pacification force, especially when they kit-out like they're going door-to-door clearing buildings in downtown Mosul, complete with armored vehicles and grenades. Talking to former military, I've been told that combat soldiers in Iraq and Afghanistan have stricter Rules Of Engagement than US police officers.
Psychologically it tends to mold the officers' view of civilians into "the enemy".
If the government really wants to improve police/citizen relations, these and other serious problems must be effectively addressed.