The (over)simplified reason: Students have no lobby. They pay no taxes and generally create no public or monetary values while going to school. Investing in them might be a really good idea for the wider future, but a legislature is only so long and noone wants to invest a fortune only to get nothing back. Later when the students grow up, they forget the struggle or even romanticize it. Then it's "today's kids" that just seem lazy and demanding. So the people that used to go to school have no intention of changing the system either. Of course there are exceptions. That's probably the only reason things are changing at all. It's happening, just way too slow.