Clinton doesn't support single-payer healthcare because the private health insurance business is a cancer so invasive that to cut it out would kill the patient.
Higher education could have been freely provided by the state fifty years ago. However fifty years ago students didn't expect to live in posh, spacious dorm rooms, eat restaurant-quality cafeteria food, take classes in sparkling new buildings, have labs with state-of-the-art equipment and brand new computers, and so on. State schools used to be institutional education. The student loan racket and resulting education bubble has created spiraling spending and outrageous expectations. Good luck dialing that back.
Or we could just cut the vast administrative bloat, and actually have professors teach classes....
That's a big part of it as well. Follow the money. And there's a LOT of money. Student loans are at the root of it, though.
We've managed to make crippling, lifelong debt a necessary part of the educational process. So much so that I almost want to tell a high school senior to skip college altogether, self-educate, and maybe get a cheap certification in Java or .NET and an entry-level IT development gig. You'll be making high-five-figures in a few years, and by the time you're 30, your retirement balance will be the same as your college-educated friends' loan balances.