My university only charged you for retaking exams (after 3 tries) and for redoing a year, if you didn't make a baseline of credits. 1 re-do was free. You can re-take any class for free as long as you're enrolled. I used this to take classes from past years that I didn't pass.
While I'm a bad example of using free schooling well, this is exactly the sort of thing taxes should pay for. If the world's richest country can't pay for schooling, ...
edit: I also remember various professors explaining how paid tuition and good education are opposites. You can't have good education with high standards, if people expect a return on their investment (a degree). How can you look someone who paid $100k in the eye and say "Sorry, you do not meet the bar. No degree"?