That's because all Mac users are adults still living in their parents' basements who spend all their time in chat rooms, playing Counterstrike, and downloading dirty pictures. Since they have no jobs, and only eat what mom buys at the store (or has pizza delivered), they never leave the basement, and subsequently have no opportunity to commit crimes. Which, incidentally, is a very good thing because given the level of psychosis of the typical Mac user, the national crime rate would skyrocket if they ever left the house and had to interact with someone other than mommy.