Police helicopters tend to be heavily concentrated in cities. A better metric might be population. The US population is only about 5 times bigger than that of the UK. It therefore has 20x more police helicopters per capita.
Police helicopters are also more heavily used in poorer (and higher crime, but also more heavily policed in general, thus inflating crime statistics) areas of those cities.
They’re primarily used to hunt for escapees, and to keep eyes on someone running or involved in a chase. Poor areas don’t have the resources to buy a police helicopter, that’s why they’re sometimes loaned to other departments in these situations. I have never seen or heard of one being deployed to control poor people.