Ah, but your not thinking of the affect of being a visible minority. Say, you have a town with 10,000 yellows and 500 reds move in to town. Every now and then, crime occurs caused by a yellow. It is expected, so when crime is reportedly done by a yellow and that yellow is at large, no one really blinks an eye to it. The yellows wont be suspicious of every yellow they see because they know that most yellows aren't anything to worry about and see each yellow as an individual. However, when the news report of a red committing a crime, it is totally different. Since they are so few to begin with, every red is seen as a potential suspect.
Even if white teens were doing the crime, any of them walking about would not be look at with suspicion like a black teen. Why? Because white people are look at as individuals. A white teen walking at night would be given the benefit of the doubt. Probably just walking home from a party or something. Crazy fools among them wont represent the whole group. A story of a white person doing something horrendous and there are comments against that one person. A black person do something horrendous, a good half the comments are against blacks as a whole. We suddenly aren't individuals but all potential criminals. It is that mindset is where the racial profiling begins.
I don't see Zimmerman as racist. I go by the original meaning of a "racist" and I wouldn't call Zimmerman that. I see him as prejudice.