What does it matter what age is set? It comes down to ability to drink safely. If you want to let your kids drink at 18, 16, 14, or 10 then let them, but let them do it at home. Create a safe environment for your children to drink.
The problem is that kids are forced to find hideouts where they can drink, then they have to drive home. It's not the drinking that's the problem, it's the driving. You hear about alcohol poisoning on the news, but it's pretty rare. What you hear about more is the date-rape and fights that result from unsupervised drinking.
I guarantee you that if you let your kids drink with you, they'd set themselves at the same pace you're drinking. Teach them how many is enough, and that they should only drink when they're somewhere safe.