The “warrior mentality” school of police training is way too popular among departments, way too stupid for their actual responsibilities, and feeds way too well into the worse aspects of Law Enforcement philosophy.
Too many cops enter the career thinking stuff like “How would I do in the North Hollywood Shootout?” and then getting training focusing on that possibility above all else, while completely neglecting the idea of de-escalation, diplomacy, or public service.
In that scenario, you don’t been racial bias to end up shooting a fleeing civilian in the back... but it certainly encourages it. Once you start being taught to view everyone as potential “wolves among sheep”, whatever biases you have are going to creep up and immediately start labeling a bunch fo people as “likely wolves.”