In some European nations, the minimum age to perform in pornographic movies, is 16. Why/how was this age chosen?

This Q is not asked to propose/advocate lowering the minimum age (18) in the USA. It is asked because I would seriously like to know why (it seems) that certain European authorities believe that 16-year-olds are somehow more “mature” or “sophisticated” or “adult” than their American counterparts, and bestow on them (under certain conditions/circumstances) responsibilities and obligations of adulthood that will probably never be sanctioned by Washington legislators.

So, by what stretch of “logic” justifies (if that’s the word) such legal permissiveness? And, I’m not just referring to pornographic performers; I’m also asking about voting and being allowed to drink wine at mealtimes.

I love pornography (as does the overwhelming majority of surveyed Americans), and am proud of my personal collection (and of the elimination of the censorship laws in Denmark), but I must confess that as “liberal” as I consider myself to be, I really do have a bit of “a problem” with the idea of a 16-year-old being legally able to “star” in a sex flick.

Your thoughts on this controversial subject?