Actually that's not mandated by law at all. What is in the law is an onus of responsiblity on service providers like Google to protect people under 13. So the

Actually that's not mandated by law at all. What is in the law is an onus of responsiblity on service providers like Google to protect people under 13. So the response of Google/Facebook etc.. simply make it part of their terms that children cannot use their services - and will be summarily deleted if they do. (Google policy not 'the law'). Net result is parents help their kids online by showing them how to lie about their age. Google's ass remains covered but they are not able to actually protect kids because they don't know their ages. Not good enough by any stretch.