The fact that the comparables are rising in price, and aid is available, makes the hikes at state schools thinkable.

The budget problems in states then force the issue.

Federal subsidies aren't the only reason for higher-educational inflation but there are growing hints that subsidies get largely captured by fee-increases. See for example these discussions:

http://www.bloomberg.com/news/2011-12-09/u-s-universities-fe...

http://www.mindingthecampus.com/originals/2012/02/why_they_s...