A large part of the problem is that the US has about 17,000 different police agencies and twice as many police officers as the next largest police state, Germany, computed per capita. Professionalism is low, training in many of the smaller police forces range from merely inadequate to none. Conservatives fight establishing standards and regulations on the level of training as undesirable federal government interference in local government.
Indeed. I would suggest that there should be no more than 51 police forces in the USA - one for each state plus the feds. In the case of smaller states, you might even want to have a single force with jurisdiction over multiple states - for example there could be a New England force headquartered in Boston, with jurisdiction over Connecticut, Maine, Rhode Island, New Hampshire and Vermont, as well as Massachusetts; Washington DC, Delaware, Maryland and the two Virginias could reasonably have a single force; as could the two Dakotas plus Minnesota; and (perhaps) the two Carolinas. None of those four regional police forces would cover a particularly large land area by comparison with other states; except in the case of the Dakotas+MN, where they might cover a lot of ground, but not a lot of population.
Of course, this idea would work best with uniform laws across jurisdictions, which might not be popular locally, but having thousands of smaller county or city forces leads to far more problems than it solves. Larger forces tend to be better trained and equipped, and resources can be allocated on the basis of need, rather than the current state of affairs where wealthy locations with little crime get the cream, and poor locations with high crime get the dregs. Laws that are specific only to small areas are just needlessly confusing in the modern world of high mobility, where a uniform legal code at least within each state would be much more sensible.
Of course, I won't be holding my breath waiting for the US policing system to be reformed along these lines; but it will probably happen sooner than effective gun control, and might help to reduce the number of needless shootings by cops.