Blaming the drinking culture itself - that American kids aren't allowed to drink, and when they do, they don't know how - is a common sentiment. It has an easy narrative, and I think it may be true. But I've never seen anyone attempt to actually verify it.

I can construct equally sensible narratives that have nothing to do with the drinking culture. I can also imagine it's not the drinking culture, but the fact that most American kids go away to college. In some other cultures which have more sensible attitudes towards alcohol (and I do think they are more sensible), I think they also tend to stay close to their parents for college.