I think places where the police still walk a beat (or other regular outreach over a wide area) and get to know the locals rarely have issues with regular people. But cities don't want to spend that kind of money on these things as they would rather not tax people to pay for it. Yet it's an investment in cities' future; otherwise you wind up with this.
I'm certainly no expert in police budgeting, but when you see some police forces literally buying tanks, at least in some cases there must be room for money to be better spent. John Oliver did an interesting story on police militarization after the Ferguson riots following the shooting of Michael Brown.