Obviously, the idea that you become an "adult" at a certain age is arbitrary, but all working societies have such for various things. Older societies were much more ceremonial about it, and sometimes I wonder if we haven't lost something important by discarding such things.

I cheered when the voting age was dropped to the draft age. I couldn't see a more obvious injustice between two activities so highly related in a political philosophy sense. I cheered even more when the draft was scrapped. American values and involuntary servitude are not a good combination. If you can't get enough volunteers for a war, you probably shouldn't be fighting it.

I don't know about drinking. I've lived in states with 18-year old limits and 21-year-old limits, and haven't really seen a lot of difference in behavior, other than teenagers not having to drive over the Minnesota border to get booze. Now THAT'S safety-enhancing, isn't it?

You can get a driver's license at 16, and be legally able to pilot two tons of metal at high speed down a public road. There are some kids who would be less dangerous with a gun.