Thanks Lonewolf 50. Having worked in Texas for several years, I too shared your optimism....and hope. I recognise that the US was designed to have checks and balances but dont accept it was as carefully planned as you suggest. The Constitution (in fact the second Constitution) was an accident from a meeting designed to raise a model Army, and John Adams argued it should be replaced by each generation. The relative lack of change and development, combined with decades of isolationism in the 20th century and fear of the word 'socialism' has left many Americans behind.
Turning to the police, I am not European, but police forces in England are based on counties so not national. There is a national training standard and each force is large enough to have senior management which can oversee standards and identify employees who need support and in extreme cases be let go, backed up by a National Inspectorate reporting to government. This is no different from any business. In the US some police departments are as small as a family business, isolated and struggling. We dont have multiple forces often fighting each other on the same turf, although there has been some slippage.