People don't go to jail for not wearing their seatbelt. Good point, but poor example
I'd cite the crack cocaine designation as a prime example to make that point. Same exact chemical substance, just put together differently, the law states crack is more deadly/dangerous, therefore should be more harshly penalized. Cocaine is more expensive, so it's more prevalent in upper class (see: white) neighborhoods, crack is cheaper and easier to produce, so it's easier to find in ghetto's (see: predominantly black neighborhoods).. See my quote from Lee Atwater on the Southern Strategy for more info