It is a good question, and it is a really complicated answer, but the short answer is poor urban black and brown communities do not have the resources to fight crime, which takes a lot of resources actually.
It takes a fully functional police department- most inner cities don’t have those. It takes stable communities, which most inner cities no longer have due to the crack-cocaine epidemic of the 80s and 90s. That completely destroyed community stability and now history is repeating itself in white America with the opioid epidemic. It is utterly destroying white communities.
The more a community breaks down, the worse it gets and soon there are no resources left and crime takes over. That is what has happened in a nutshell.