I respectfully disagree. I think it's working very well. Unfortunately, good news doesn't sell, so the media won't print all the good things that LEOs do every day. All we hear about are the bad things that a few do.
Some places yes, others not so much. Under Guiliani, and his "small crimes" enforcement policies, it was working pretty well in New York City, not because of it's gun control laws, but in spite of them. In DC, it doesn't work for spit. It doesn't depend as much on police as it does courts and politicians. If the courts put the perps away and the bureaucrats and politicians devote enough resources to keep them away, then there is a deterrent effect.. except in those sub cultures where getting sent to jail or prison is a badge of manhood.