This is roughly how UK student loans work too. You typically borrow £55k for a three-year degree, but then repay at 9% of your annual earnings above £26,575.

There's also a rule that the remaining debt is cancelled 30 years after you graduate. Most people (perhaps not most programmers) won't repay the whole debt within 30 years. So for them, this is essentially a kind of tax, rather than a debt.

https://www.moneysavingexpert.com/students/student-loans-tui...