@parados,
As in Ferguson a lot of places with the population unhappy with the police department the police are under the control of the courts and the local politicians and not only need the politicians must stand for re-elections but the judges in many cases also.
Seems simple when you have a population that is overwhelming blacks to vote in both judges and politicians that would give them the policing they are more happy with.
Whole police departments in the south florida area had been done away with and the job of local policing given to the county when the local voters are unhappy with the local police department.
Why the need to riot unless only a small fraction of the population is unhappy with the police department.
Seem more likely that only the criminal elements are unhappy in such areas.