This essay (which is fantastic and you should read) summarizes a key point that I make very often about police officers: they are not here to keep you safe. They are here to write tickets and clean up the mess. Whether that's showing up 20 minutes after some guy in my apartment complex has a violent raging meltdown (just last week!) or writing you a ticket for jaywalking it ends up being the same thing: you need to be able to avoid attracting attention from criminals AND cops, because both will treat you as an engine for extracting revenue.
It turns out that THREE-FOURTHS of Ferguson, MO had arrest warrants at any given time. And that is for civil infractions, like parking tickets. Not, you know, actual crimes (felonies or misdemeanors). If you are poor a parking ticket is a burden, but how are you going to pay it if you are in jail?
Speaking of extracting revenue, here is an illustrative pull quote from that essay on Gawker:
Obviously, this picture has almost nothing to do with anything we normally consider "justice." Still, if the image of police terrorizing and manhandling citizens over parking fines seems bizarre, it's partly because we tend to forget who and what the police actually are. The police spend very little of their time dealing with violent criminals—indeed, police sociologists report that only about 10% of the average police officer's time is devoted to criminal matters of any kind. Most of the remaining 90% is spent dealing with infractions of various administrative codes and regulations: all those rules about how and where one can eat, drink, smoke, sell, sit, walk, and drive. If two people punch each other, or even draw a knife on each other, police are unlikely to get involved. Drive down the street in a car without license plates, on the other hand, and the authorities will show up instantly, threatening all sorts of dire consequences if you don't do exactly what they tell you.
The police, then, are essentially just bureaucrats with weapons. Their main role in society is to bring the threat of physical force—even, death—into situations where it would never have been otherwise invoked, such as the enforcement of civic ordinances about the sale of untaxed cigarettes.
Welcome to America.