It doesn't matter since she is pandering for votes... Her track record for telling the truth is a great example.
I can see reimbursing college graduates who got a good 3.0 or higher GPA and are working towards fields we need like medical, nursing, trades, engineers, etc. I'll gladly pay taxes for that.
The idiot with a gender studies degree, however, should have to shell out their own cash for their mediocre college experience. Same goes for the nitwits who party through college and then dropout.
Unfortunately, paying out people's college also means corrupt rich kids and entitled asshats, Warren's voting base, would steal all potential free college spots from legitimately poor smart kids.
Since the government sucks at regulating the basics, paying out free everything isn't looking too good for the U.S. And you can't straw man this with other EU countries, since their populations are the size of a U.S. state and even then they have limitations in place... it's not a free for all.