You're assuming that this person is in the US. Alcohol is treated far more liberally in other places. For example, in some places it is legal for restaurants to serve alcohol to minors who are accompanied by a parent...

Another thing: I fundamentally disagree with certain age rarings for kids content. Some explicit violence is rated OK for young audiences, but insert a swear word or a some skin and the age rating is bumped up? This rating system is nonhelp at all. I have to review each bit of content anyway before I can be certain.