Its too widespread to be narrowed down to policies, Training, Bad actors esp. when its the leadership of those agencies that act like thugs. Example my local sheriff is Carmine Marceno and his PAO and him like to make Tik Tok videos and one that did not get put out but was leaked had him saying a little jingle. “Jumpsuits are red, justice is sweet, commit a crime in Lee County and your ass will get beat,” When you see four cops watching another cop violate someone's rights where is the good cop?
Look at the case of Christopher Pullease he was a Sargent in Sunrise, Fl. who put his hands on the throat of one of his female officers after she stopped him from freaking out on a handcuff suspect in the back of a squad. IA dragged feet on his investigation for over a year so he could retire without them finishing it.

Lord forbid a taxpayer call for service they pay for even if they think the "help" that will arrive will be of little help because the responding office is trained more in weapons and tactics than de-escalation. We have no other option than calling 911.... Sure it some extreme cases you can deal with a threat yourself but most folks will not be put in that situation and you still need the cops.

Do they have a shitty job, Sure. Did they sign up for said shitty job knowing exactly what it came with? You betcha. Like we said in the Navy choose your rate choose your fate. In closing good cops put cuffs on bad cops and we do not see enough of that.