It might also be because military equipment is statistically more likely to be acquired by departments in more dangerous environments. Though I still feel the

It might also be because military equipment is statistically more likely to be acquired by departments in more dangerous environments. Though I still feel the explanation is a positive feedback, where being more aggressive causes more aggressive behavior to normalize faster, causing more aggressive equipment, causing police to feel more like an occupation force rather than civil servants, causing more aggresive behavior, and so on.