It's much less mysterious when you consider socioeconomic factors. In particular, they concentrate in neighborhoods which are vestiges of midcentury economies of scale (i.e. factory jobs), and are now hopeless. Urban police are pretty good at stopping violent crime from leaking into white professional neighborhoods, which is arguably city institutions' true priority.

Police tactics are only going to get you so far in communities that (justifiably) see the police as an oppressive enemy faction, where witnesses don't talk to detectives and juries don't convict.