I just finished my first year at the local community college, and there are huge numbers of people there who are just plain not very smart. So, I can see your point, but you fail to look at a broader picture... There are also a large group of people returning to college after decades of employment elsewhere, they need a refresher course in the subjects they haven't touched since high school, and maybe won't use in their future degree either, but since we are stuck on liberal education in the USA, they have to re-learn it. Then, there are the people (like me) who aren't great at math, but are exceptional at other subjects. I got an A in my math class last term, but yeah, I had to study. If people were barred from an education simply because they weren't skilled in a subject that they didn't use and won't use in the future, that's pretty impractical and hardly fair.