That's not what people are asking. They are asking why this racists white guy isn't in jail awaiting trial, conviction and execution for planning the murder of this innocent black child.
And that's the problem.
1) A very aware (boarding on paranoid) citizen sees something suspicious (the guy did not "live" in the neighborhood, there has been crime, it's night time). 2) Calmly call the police and can't initially tell if the guy is white or black for sure. He only answers the 911 operator affirmatively when the black male approaches him. 3) He stops following the suspicious male when the male takes off running according to the 911 calls. 4) There is a physical confrontation moments later that finds Zimmerman with a bloody nose, cut on the back of his head and wet grass on his back. 5) Witnesses testify to the white guy yelling for help and getting beat up. 6) Media fills in all the blanks for viewers and listeners with speculation.
Hopefully this is my last post on the subject, there being no point in arguing when none of us has sufficient facts. But speaking of sufficient facts, there's a map up-thread that shows where the shooting occurred. Looks to me like Zimmerman would not have driven his truck back there, but went on foot. I would ask you to consider -- not explain to me, mind you, but just consider -- how that squares with your assertion that he stopped following Martin when Martin took off.