Police are above the law, or they are the law, as they are the agents of the ruling class. They scarcely protect citizens because they have no incentives to. They get paid one way or another as their relationship with citizens obviously is not voluntary, and their departments have no competition. Would you feel the need to go off and fight real crime under such conditions? No its dangerous, you would be more content to do miscellaneous shit like racking up ticket income from people who commit victimless crimes, like your superiors want you to do. You of course couldn't rock any boats, but you can easily get by just fine as a douche who provides little to no services.
And since the state has a monopoly on law/legislation, in the event of conflict between the state's agents and citizens, it will of course rule in the favor of its agents (even though they might have been the aggressors). A lot of cops get their rocks off pushing people around, we've all witnessed the "jackboot" psychology as Alex Jones would say. Just as democracy attracts the best liars and people with the least amount of moral scruples to become legislators, I imagine the same can apply to the legislation enforcers. Though of course this is a generalization and there are rare exceptions, the ingredients are all there to produce what can only laughably be called "service and protection" at a high and involuntary rate.
The only thing tugging them along is the need for at least the guise of providing a service, and the slow nagging of the political process. But there is an awful lot of propaganda surrounding the "boys in blue", and people can't imagine things being any other way to begin with.