Well perhaps I should have said, they don't have to. Right now they need not bother to charge at all. And how they set the sticker price is only a small part of the picture anyway, since they gather near-perfect information about your parents ability to pay (or to donate!) before anything gets agreed.

This source does not have any information related to loans availability correlating with tuition prices. Are you making the assumption that tuition hikes can only be caused by loan availability?