I saw my first Playboy centerfold in 2nd grade - 8 years old. Didn't kill me.
I don't quite understand what you're asking. For a US person to look at pictures of sexualized girls under the age of 18 is illegal, regardless of where the pictures are being hosted. Example - Traci Lords videos are legal in Canada, because there the law is 16 instead of 18. But for me to buy one and watch it here would be illegal, even though the product was obtained legally. How they enforce that, I don't really know.
On the other hand, I think porn is kinda like cigarettes in the hands of minors. I believe the law is that you can't sell them the product, and they can't buy it, but once they get their hands on it, it's legal for them to possess it. A 10-year-old kid could never be arrested or detained for smoking - only for buying cigarettes. Likewise, I'm pretty sure that for a child to view pornography is not really illegal.
However, most reputed adult sites require visitors to be over 18, and cooperate fully with web blockers like NetNanny. Because porn operates on the razor's edge of legality as it is - they are so nervous about what could happen if they step out of bounds that they are willing to self-police themselves. I think this is probably a good thing - a state in which the burden of public "safety" is transferred to the pornographers themselves.
Fuck the US. Oops, I mean "Yeah,Yeah,USA!" Please don't send any agents to my house.
