At the risk of giving away my open secret of age, I was of age when the drinking age was lowered to 18. It lasted a few years, but then they realized a few things. 18 year olds were still in highschool- my husband would sign himself out of school and go to the stripbar across the street for beers and naked dancers. Many did. Drunk driving deaths among that age group (under 21) were way up. Driving license at 17, drunk at 18? Didn't work.
Hell, some 50 year olds have no business drinking, but at 18? Responsibility never entered the equation. College kids drink now underage...at least the 21 year-old law gives some semblance of rule.
since i am typing this after my 3rd drink, not sure if it makes sense 