Generally, they have pictures of one or more legal adults participating in activities that they consented to, while being photographed and videotaped, again with their consent.
I honestly don't think I've ever seen a porn site pandering to children, much less trying to get them to follow them to their van. Remember, most pornographers are in it for the money, that's it. Trying to attract customers under 21 would be an invitation for legal action, which hurts the bottom line. Predators that try to lure children tend to use chat rooms, web sites leave too much of a trail.
Thanks for explaining that to me..I am not a prude but can't see why anyone would want to visit a site like that.