That or you can go to war at 18 and get yourself killed but if you want to drink alcohol welp nope I can get myself killed but I can't take a sip of a liquid till I'm 21
That sucks! I totally agree with you having two sets of laws that deal with being an adult is ridiculous! It should be 18 and your good for everything!
On top of that most places don't lets you rent a car until you are 25 or others put up a massive fee if you are under 25 and there are many more examples of stuff like this if you look hard enough