In the USA, police shot and killed 1,004 people in 2019. The comparable figure for the UK is 3, for France 26, for Germany 11.
The USA has 655 people in jail per 100,000 population. The UK’s figure, high by world standards, is 140. The Netherlands, 54.
The USA had 12 deaths in police custody per 100,000 arrests last year; the UK, two.
US police make three arrests per year per 100 population; the UK, a more typical figure, one.
Social provision in the USA is weaker than in most relatively well-off countries. In many well-off countries, even in poorer districts, generally “the state” means health care, schools, benefits, etc. as well as cops; in some areas in the USA, there is much less to see other than cops.
Black Lives Matter, a loose network set up by Patrisse Cullors, Opal Temeti, and Alicia Garza in 2013, has a detailed program to restructure policing (see here and here) as well as its headline “defund the police” call.
Public police forces, as distinct from private enforcers, developed later in the USA than in Western Europe. They were preceded by more ad hoc “slave patrols”. They have long been notorious for being a law unto themselves. Efforts to reform them date over a hundred years.
The US police are also more militarised than European police, with a special program initiated by Bill Clinton to have surplus army hardware passed on to them. However, they are generally less numerous (per population) than European police. Their pay varies hugely from place to place, but is often relatively lower than European police rates.