Unfortunately, in the States, violence on over-the-air and basic cable TV is pretty much okay, but the moment you even start to think about sex, oh boy, are you in trouble.
But I look at it like this: I agree that the censorship is ridiculous. Every time so much as a bare butt makes it onto TV, the same shrieking, self-appointed moralists climb out of their hole to tell us about "the children."
I ask them this: If their kids (assume anyone under the age of 12) are watching South Park, exactly how great a job at parenting could they possibly be doing?