It's basically a simplification for life for some people. A lot of people don't like to think in nuances. Cops have a dangerous job and now that a large portion of the general citizenry hate them they have even more reason to be jumpy and sometimes aggressive. I think politicians could help a lot by ending programs like civil asset forfeiture, militarization of the police, etc. There is big gap between militant cops in small towns beating heads and what seems to be letting criminals do whatever they like in San Francisco downtown and then the DA letting them go because they did something less than shooting someone. I, for one, choose to live in a place with relatively stable "small town" cops even though they have sort of a bad rap in the neighboring city because they actually do patrol. I'm a brown person who has had zero problems with cops even though I have a lead foot.