For every dollar in tuition, >Y% must be spent on qualifying direct educational expenses. E.g. teaching faculty salary, etc.
If a college fails to meet that threshold, and spends too much on non-qualifying costs, they are required to rebate the difference to students.
If a college refuses to do this, they're no longer eligible for federal educational money (Pell grants or loans, etc).
Then let colleges optimize themselves to get under the limit.
It caused a lot of scrambling and long-overdue efficiency improvements in another legacy, slow-to-change industry (health insurance).