Keep in mind that LEO officers were given a far greater benefit of the doubt and had far less constitutional constraints(i.e. No Miranda rights until the late '60s, more free to beat up citizens capriciously). Consequently, LEO’s had many more opportunities to abuse their authority and random citizens, especially young people and those from marginalized groups.
A HS history teacher I had who grew up in the '50s and early '60s recounted the local police in his White majority suburban town not only brutalized marginalized groups, but also any young person going about their daily lives.
He himself was beaten up by LEOs on a few occasions just for being a teenager despite being White himself and from a solidly middle-class home going about his business to/from school and most of his friends experienced the same.
However, because of the overwhelming 50’s style conservative attitude among parents of his generation and the town which gave LEO’s the overwhelming benefit of the doubt, they knew they couldn’t tell their parents because they wouldn’t be believed. It was only decades later that some of their accounts were confirmed and corroborated.
Also, right after WWII, there was an outright insurrection against the LEOs/local government of one Tennessee town by returning GIs because of a long history of police brutality and serious corruption from the then dominant LEOs/local government before the insurrection forced an effective end to such practices, prevention of more attempted corruption at the ballot box by the then prevailing local govt/LEOs, and a change in local government/LEOs: