They arent motivated by an infrastructure game like
@Anarchy pointed out, but he is correct about that being the system. The motivation of these people is dominance and impunity within the law that hands them the weapons and the excuses.
Legal impunity enables their sense of entitlement.
I'm not implying any hidden agenda behind abusive cops
it's simply the inevitable outcome of it being a coercive institution.
Before delving any deeper into it, it's worth remembering that before the middle of the 19th century, there was next to zero state sector policing in the English speaking world.
There were one or two examples, for example the county of Middlesex, where most British members of parliament either lived full time, or at least had their town houses, had a county police force from the mid 18th century, but that was a way for the politicians to spread the cost of defending their personal property (against gangs of British soldiers who were returning from Britain's long wars in Europe, and who had lived for years by stealing from other people) onto all residents of Middlesex, rather than paying the cost of defending their personal property themselves (in short the politicians distributed and socialised the costs - and received the concentrated and private benefits).
so - state sector policing is relatively new in our society (the institution is only about 150 years old) , and is certainly not an essential ingredient for a society to develop or to prosper.
State sector police are certainly not the only sort of "police" either. In Britain and America they're outnumbered at least three to one by private provision at all levels - from ultra high level specialist security hired in by banks and insurers to investigate and recover theft and fraud, right through the spectrum of protecting high value cargoes, to the humble mall security man and building site night watchman. There is also charitable provision to poor and minority communities (eg Dale Brown's threat management centre in Detroit).
I hope that those few examples show that security can be and is currently provided (at all levels of complexity and in much greater quantity) by private provision - it isn't a good/service which necessarily requires a coercive state to provide it in the form of a monopoly (which inevitably suffers from all of the problems and abuses of monopolies).
OK, with that out of the way
there are two ways for people to organise and coordinate with each other;
where we choose who's examples we may want to follow, who we would like to (or least dislike to) work for, who we want to spend our time with and how we want to spend it.
within that consensual side there are also institutions which prevent conflicts from arising (for example generally accepted conventions for deciding who has the right to use and dispose of certain goods at any particular time) and options for peacefully resolving disputes and redressing torts when they occur.
Our employers only have the "power" over us that we allow them to have, before we leave them and go work for someone else.
We are of course constrained by the laws of nature - two people cannot travel the same lane on the road at 80mph in opposite directions at the same time...
where someone else decides and forces their decisions and whims onto us (and probably gas light us into thinking that we chose those whims by voting - or "that's how things have to be").
state sector cops are the muscle/thugs who enforce that coercion.
it's no surprise if you find your personal sense of justice, and safety being offended by a steroid fuelled fat blue line!
