Frankly I find that the people who have most problems with police are assholes themselves.
That's mostly true. But the police are in a special category, sort of like airplane designers are. They had better get it right not just most of the time, but all of the time.
And that's actually not that hard to do. Be polite when talking to citizens, use force only when necessary, etc. Sure, there will be times when quick judgment calls will have to be made, and no one will be perfect then.
But in general, it's not too much to ask for cops to behave decently in everyday situations. And many do. But not enough.