I have mixed feelings on this.
First, you would think that anyone should be able to have a beer anytime they want, but since there's a risk to the public someone had to come up with an age of responsibility just like they did with calling kids under 17, 16 or whatever minors who can't engage in sex with people 3 or more years older than them. it's arbitrary, it doesn't take into account the different maturity levels between people, and it's a broad brush solution to what many see as a problem in need of a solution. Is it right? It depends on the person and the situation.
When I was a teenager the drinking age was 18. With fake ID I got into bars at the age of 16. I used to drive when I was totally sloshed and I'm lucky to be alive today and I never got arrested for a DUI although I was stopped a ton of times and told to sleep it off. Times were different back then - today my life would be ruined if I didn't have a driver's license because of drunk driving.
A guy in the military should be able to have a beer. how about we let soldiers drink on base only and can't leave if they've had too much or whatever amount someone decides is not safe. After all, in Texas a minor can legally drink in his house if he is with a parent. So why not a soldier if they have someone monitoring how much they drink? I mean, c'mon, these guys go through hell and need to blow off some steam.
On the other hand, I don't want my kid drinking while he's still too immature to know when to stop. These days thrill and binge drinking lead to rapes and/or accusations of them and kids seem less responsible than they did during my days.
So I personally think the drinking age should not be too low, 21 is good, 25 is better unless that person is with someone who will be legally responsible for his actions. Yes, kids will get their hands on booze, but it will happen a lot less than if some 18 kid buys booze for his 16 old friends who then get their 14 year old girl friends drunk.
And what the F is this obsession America has with getting high? Is Obama that bad that the only way to forget about his ineptness is to get hammered?