Where are all those good hearted cops when their colleagues murder innocents and uphold the inequality system? How many of them testify against the rotten apples? On which side are they when people protest fascism on the streets? Or when fascist dictators take over?
Look around the world at how many defacto dictatorships exist. How many of them are supported by the police?
The police, as an institution, is the strong arm of the ruling class. It always has been. If you look at the history of police forces around the world, that's how most of them came to be. It's their purpose.
It's also an institution that tends to attract personalities that get off on power. The US is completely out of control on this issue but that underlying issue is not exclusive to the US.