It sounds like a rare old clash of cultures here. What surprises me here from the American side is the assumption that teenagers are likely to drink and drive. I do not deny that it happens in the UK, but I do not believe we work on the assumption that drunk teenagers will attempt to drive a car. I also believe that such an assumption would be unjustified. People do stupid things when they drink. However, I do not believe most teenagers get drunk when they drink beer. Some do and most do not.
In Germany, where I live, sixteen year olds can legally drink beer in a pub or a restaurant until either ten o' clock or midnight. They are not allowed spirits. Most teenagers drink responsibly for most of the time. The drinking age is eighteen.
I am struck by the assumption of the Americans that driving a car is the only practical form of transport. I assume that because of the greater distances, there is no alternative in many cases. I guess we just have a different culture in Europe and we find it puzzling that young people should be prevented from drinking at all.