<p>Many more students at large publics are more or less independent from parents, some of whom could have afforded to pay but chose not to or the kid wanted to do it on his own. They work part-time and graduating in four years is pretty far down the priority list. Outside a few to privates most don’t really offer all that great fin aid and the nut is MUCH larger. Lots easier to write a $4000 check per semester than $20,000.</p>