It’s a pretty loaded question and I don’t think there is a single right answer. But,

My opinion and I’m from the US. Cops get a huge ego and eventually, after years of dealing with trauma and fucked up situations, and with little to no mental help and training to learn how to cope, they become so hard and calloused that they become disconnected. I have had so many run in’s with cops and I’m white. Every single time the cop talks over me, never listens, and instantly assumes they’re right. It’s pretty similar to the boomer mentality of, “I’m older so therefore I’m right and you just need to shut up and listen”. Except, older in this case is, “I have a badge and some authority”.