Kiwiblog has a thread on this subject and reading through it am I glad that a single stubbie makes me sleepy thanks to my upbringing .. getting pretty drunk for the first time at 22yo [despite two years in the army and earlier 10yo being supplied with a couple of gin and oranges by best man and groomsman at a wedding. Groom was a army major and they were in the army too] and disliking the hangover and waste of money; though my guardian let me taste her Guiness [horrible!, put me off it for life]and have a shandy when out riding our bikes at around 12yo and virtually not drinking until my fifties when it was wine for medicinal purposes .. red wine good for the heart? But I guess I was also lucky in one sense that I didn't grow up with a bunch of freinds through until adulthood so no peer pressure, though obviously I missed a lot of fellowship becuase of that.
I object to any age limit for parents supplying a drink, suitably watered down maybe, to their own children, but not others without specific permision from their parents. If a drinking age make policing easier I agree with that, it makes better sense than raising the buying age. Agree that prohibition makes it more attractive for the consumer trying to rebel from their upbringers and the slygrog merchant making a buck from selling the stuff. The gangs have enough options without adding alchohol to the list of drugs they would supply.