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.
Which law? I'm not American so I'm not familiar with this. But there's certainly plenty of kids on other sites that are used for communications, so what makes Google delete kids' accounts?
The tldr is that it's a notoriously difficult law to comply with unless (1) your site has limited userbase or functionality, or (2) you delete children's accounts on sight.
I haven't read through COPPA, but I believe that Google, as a US company, has to abide by COPPA restrictions, regardless of where they're storing data. (It might even apply to non-US users...) As the user above pointed out, COPPA is really, really hard to 'get around.'
I've always been confused by this. Does "as a US company" mean that it's HQ is in the US? Or that it is incorporated in the US? Or just that it does business in the US?