Agreed! But remember, there are similar problems for fiction in some countries. Hence the underage tag: if it wasn't clear, artwork like any other work (text, video) is subject to the AO3's mandatory warnings, one of which is "underage." The reason for that is precisely what you're talking about: that in some countries, even fiction about minors can be legally problematic. So art will be like other archive works and require those tags for filtering/sorting purposes.