This is the answer. Lenders would then have to do proper qualification on borrowers, would be more limited in their lending, and this would put downward pressure on tuition.
As an example: say you work at target for 2 8 hour days on the weekend making 15 an hour and with a 36% debt-to-income ratio limit, you could afford a payment of $374.4 a month. $15,000 punched in a 30 year repayment at 29% interest rate equals a $362.57 payment. So you might be able to do it but I would hate to be working every single day between weekend work and weekly school and that is assuming an entire 4 year degree could be pushed to to $15,000.
It would also create a massive false negative problem where kids whom could have succeeded never got to go to college because banks would get so picky if they even were too somehow make a loan like that work.
[0]: https://educationdata.org/college-dropout-rates#:~:text=In%2....
Or cut out the middle-man entirely and have the government provide college education for free.
Apparently the average community college costs about $10k to graduate from, less if you're on a 2 year degree.
Cue "that's not real college" crowd, of course.
This was very normal and possible when I went to college. I could work part time during the year, full time in the summer, and pay my tuition. It didn't leave much free time but it was possible and a lot of people did it.
These days tuition is so high at most universities that it just isn't possible. Yet they are not actually teaching anything more or any better than they were back then. It's just way more expensive.