Cities just happen to have a majority of the population and a lot of minorities. It's also harder to hide things in cities. Small red towns are generally much worse and things rarely come to light.

https://fivethirtyeight.com/features/police-are-killing-fewe...

edit: Regarding cities having a much larger percentage of minorities: https://www.pewsocialtrends.org/2018/05/22/demographic-and-e...

It took me all of 2 minutes to look these things up, the fact that you didn't just shows that you care more about a particular ideology than facts.