Pretty sure I remember reading about the FBI taking people down for this kind of thing a few years ago, so I wouldn't be too quick in claiming it's legal, as some are doing. I'm amazed sites like that still exist, let alone are (presumably) able to process payment.
It's also mind-blowing that someone would start a thread and so matter of factly talk about accepting a job working on an underage site, as if it's the most normal thing in the world.
Not much surprises me these days, but this is... wow.