It depends on which police force you are talking about as well. I live in Catalunya, and the local Mosos police force is the main police here. They have quite a few stories of bad hiring practices, silencing ex cops who speak up etc. However, I have also met good people trying make a difference, so I think it all comes down to who you talk to.
This whole police problem in the US looks to me like a few bad people that makes all cops look bad. Add to that, a biased hiring practice and coverup / protecting wrongdoers, and you get the situation you have in the US today where people don't trust the Police. It then becomes a worse and worse as the rift between civilians and police grows bigger.
I think the problem is really in management, where everything becomes political. No one wants to sound like they are soft on crime, so they all make speeches of fighting crime, war on drugs, etc. The wording says it all: "Fight Crime" and "War on drugs" are both very powerful messages, meaning more arms, more violence and not a peaceful solution. Add to this, the short time-spans of some of the turns that these people have in office, its no wonder that no one is trying to solve anything. It would take too long to see results, and they would not be in office or at least fear that they would not be in office. So, short turn patches get applied with a lot of force.
I don't know a solution, but at least we should look at removing as much of the political and financial pressures from police departments, let them hire better people (and yes they might leave after a few years, but that's just how things are now). We also need a cleaner and more transparent system to deal with wrongdoing, whatever happened to Internal Affairs? Are they still a thing? Have they lost power or have the political hands gotten involved there as well?