Police in the us are more likely to be heavily armed and paranoid because they are armed, and are often trained to be paranoid.
One interpretation of this data is that police are systemically targeting lesser-armed areas where they have a fire-power advantage. Policing "their own people" is taboo and dangerous - they are outgunned. They post-hoc rationalize this racist bullying by pointing to all the crime they found, despite only looking in one place.