I mean legally they shouldn't be with COPPA and all that, otherwise there are far more regulations in relation to their privacy, the two ideas of toning it down for children and not following children's privacy standards would visibly contradict each other. Doesn't stop children though since the most blocking then from registering for most web sites prematurely like that is a text box that might as well say "I am above 13 or willing to claim I am". A more cynical person would say that's by design but there really is no unintrusive to verify that either otherwise such a thing probably would be enforced for legal reasons.