Now, surely you all realize that "mature" and "adult" in this context means having reached a certain age, the stuff obviously being legally prohibited to minors. Other meanings of the terms, as used in other contexts, are irrelevant to these labels. What's next, the old "Why do we drive on the parkway and park in the driveway?"

Compliments of your resident curmudgeon.

(Not done with intent to belittle anyone, but come on, it's a lame point. We all know what "adults only" means.)