They do a good job protecting the property of the wealthy by harassing the "undesirables" to move to designated areas, and that's why certain parts of town are "ghetto". It's a bit of an unspoken rule that as long as the dirty peasants stay in the ghetto they'll be less likely to be harassed. You generally won't be asked where you're going or why in the sketchy part of town, but looking the wrong way and straying in to a nicer part of town... you'll have 3 cruisers on you in 5 minutes.

As long as the police have the support of the upper class, it doesn't matter that the majority of us have lost all faith in the police.