Yeah it's dumb, but to be fair this is something where we get to have our cake and eat it too. The moralizers / religious / people fairly concerned about drunk driving get to feel good and maybe have a positive effect, and everyone that is 18-21 still gets ready access to alcohol at school where the need to drive is substantially reduced. Whenever I wanted to get alcohol at school, I could easily get it and the situation was the same with all of the friends I knew at other universities. If you don't go to school you get access through work friends.