In Europe, about 35% of HS grads go to college. Here the figure is almost double that.
I think some of this is that our HS system is not as rigorous for that top third, and kids go to college to catch up on whatever they failed to learn in HS.
Another thing about college in Europe, you basically take ONLY courses in your major, you don't take English and history and liberal arts if you are a science major. So, they get a more extensive study in the field of choice undiluted if you will by those make up courses. They are assumed to have learned a foreign language in HS, and their own language, and history, etc., so they come out of college with a more extensive knowledge in their field of study.
We here have made college an egalitarian "experience" with kids below the mean in academic achievement attending.