My anecdote: undergrad in Montreal, so the drinking age was 18. The first semester of first year involved quite a bit of heavy binge drinking, but by the time finals came around, I'd say that most of us (even the new drinkers) had acclimated and were drinking at a slightly more reasonable level. I have a hunch that being able to drink legally in highly social settings (the common room, clubs, bars, etc) is massively helpful in establishing healthy(er) drinking norms.

There isn't nearly as large of a frat/'Greek Life' culture in Canadian universities as in American ones, as far as I can tell. This is despite the fact that Canada and the US have very similar university systems, with students often crossing the country for school (unlike in Europe). I suspect that part of the reason for this frat disparity is that there's not so much appeal for frat parties when you can legally buy your own booze or go out to a bar/club without needing a fake ID.

Of course, alcoholism is a major problem in Canada as in the US.