From The Government’s Bailout of College Grads Continues:
Repayment caps such as those offered through income-based repayment and other policies put no downward pressure on college prices. After all, why should colleges reduce tuition rates if the government keeps increasing student-loan subsidies? Making income-based repayment options even more generous will continue to enable universities to raise tuition and fees, confident that students will have access to a deep well of federal loans and grants, which will be paid-off through IBR and loan forgiveness on the backs of the taxpayers.
Same topic from McArdle: Cheaper Student Loans Won't Curb Higher College Costs
Taxpayers already pay for high school. That ought to be enough.