useless mexican police

While people are assaulted on the streets, while drivers are left without the cars at street corners, while families are left without children for weeks and get a piece of the victim's ear or finger for some million of pessos, I was stopped at a corner because I claxoned. I did it because at every corner somebody jumps on my car to clean it. My car is cleaned every week with proper products and I don't intend neither to get a scratched or dirtier car, nor to see a pistol pointing my head. I claxoned, the policeman stopped me and asked for my papers. This time I was lucky. Next time I could be killed. Policemen are there only when you don't let the guys "clean" your car. Mexico has ten kinds of "policias". Could I know, please, what are they doing?