This video of an NYPD cop body-checking a cyclist is a little scary. I'm sure the cyclist walked away, at least. Or would have if he hadn't been arrested for resisting arrest (???). Getting knocked sideways and not into traffic is probably the best case scenario, and at least the cop wasn't in a car or on a horse, where he really could have done some damage.
But yes, if your society offers a career that involves wielding authority over fellow citizens, then that job will tend to attract a certain number of people who are interested in that aspect specifically. It would be possible to try to counteract or preempt that dynamic in a couple different ways, I think, though it seems like right now most people are content with the status quo.