Rising tuition prices at colleges and universities and the relentless growth in student debt in the U.S. have fueled calls for tuition-free college education.

Student debt stood at $1.4 trillion nationwide as of the fourth quarter of 2017, according to the Federal Reserve Bank of New York. Federal Reserve data show that more students are taking out loans and the average size of those loans is growing—and repayment rates have slowed.

...