Cops probably view poor uneducated and obnoxious kids as subhuman. A lot of these kids are foul mouthed, disrespectful, and psychopathic.
Dehumanizing a class of people, even if they be without any sense of morality, leads to overreactions by cops.
There is no law against being raised in a barn. Cops aren't going to teach them any lessons by beating them up.
"You will respect mah authoritah."
No they won't.
Cuff 'em, shoot 'em, or release 'em. Everything in between is unproductive.