Please read the node Some thoughts on drinking age limits in the United States
to get my writeup in context. This is a long post as well, so be warned :)
Allow me to draw upon an analogy from my personal experience. I live in a university residential College in Australia (ie most of the residents are teenagers). Technically, my Colllege is a 'dry' College (ie no alcohol consumption is permitted). However, the Dean of the College takes a relaxed interpretation of this rule. Our College tends to have this policy instead:
"You can drink alcohol in your rooms and at College events. There is to be no drinking in public areas within the College and you must not show adverse effects of alcohol (ie rowdy behaviour in College will not be permitted)"
There is another College in the area which has no policy on alcohol consumption - basically, they can drink when and where they like.
Finally, a College just up the road has a very restrictive policy. The residents there are not permitted to consume any alcohol while in College and random room searches are done to check for alcohol. If you are caught with any alcohol while on College, it is an instant $50 fine.
So what is the results of these three policies?
In the College with no policy, there are always a bunch of residents who are drinking. There is a very boozy culture at that College with the associated problems - eg sexual harrassment, intimidation. I don't want to sound like that College is a shithole or anything - but those problems do exist and are known.
The College with the ultra-restrictive policy naturally has no drinking on the College premises. However, when the residents go to the local pub or they have external events away from the College admin, they all go crazy. With no idea how to handle alcohol or what their limits are, they often become blind drunk and invaribly they cause trouble at these events.
I'd like to think that my College has the right attitude. They encourage sensible drinking and it is possible to safely find your limits while at Collegge.
So to tie it back to the original node ...
I definitely don't think we should be restricting alcohol consumption like during the Prohibition nor should alcohol curfews be introduced. They would be expensive to police and would be as ineffective as a total ban on alcohol. And just like the College with the ultra-restrictive policy, simply hiding the problem doesn't prevent them from occuring.
However, just like the College with no alcohol policy, I don't think that a fully unrestricted drink driving age should be permitted either. When people are young, they like to experiment - except, experimenting with drinking and driving are lethal combinations. And worse, other people can be inadvertently drawn in.
I think a moderate policy needs to be taken. One where drinking is not demonised, but that people are strongly encouraged to be responsible and that an environment is provided where drivers are learn their limits.
In Australia, our legal drink driving age is 18. We also have highly effective massive media blitz warning about the effects of drink driving which show bloodied and dead people trapped in their crashed cars. We also have a vigilant police force which frequently set up road blocks to test for drunk drivers.
In addition to this, for the first year after you get your drivers license, you are not permitted to drive with any alcohol in your blood. If you get caught, bye bye license.
All this works fairly well (you can't stop all drink driving obviously) in providing an environment where young people can be encouraged to drink and drive responsibly.