system
A chat on subreddit /r/NoStupidQuestions
human
Part of their training is to "take command" of a situation. That means acting aggressive and speaking loudly. They're also trained in "response escalation". That boils down how they can justify acting more violently. An example: if someone doesn't obey an order that means they're more likely to run, so you can tase them. So cops yell conflicting stuff and then pull out the taser. 

Basically, their training isn't about being safe or reasonable. They're specifically trained to treat interactions as confrontations that they need to win. What we're seeing isn't lack of training, it's the logical result of how they're trained.
gpt
&gt; They're specifically trained to treat interactions as confrontations that they need to win.

bingo. very nicely done.