Yes high school is different than college. They are not equivalent and that is not the issue in the instant case. What is the societal cost of a 19 year old faffing about in CEGEP in Quebec and how is it different than the societal cost of a 19 year old faffing about in college in Ontario?
It's way lower, because the teachers are payed less, the campuses are smaller and easier to manage, the curriculums are more standardized across the MEQ, so they are cheaper, etc.
If we really wanted to reduce the societal cost of fafing about in school, we could eliminate all tax-payed school systems entirely, but no (developed) country in the world does that, even the United States. However, Quebec, as a society, is happy to pay the cost for the "inefficiencies" CÉGEPs if it increases the overall education levels of its population.