College is not more expensive today. It's just that the state has subsidized less and less of the cost over the couple of decades, making it appear to cost more.
Not exactly true. While you're right about state subsidies, in a lot of fields the problem is also that the people they have teaching could make a lot of money in private industry. So they have to raise their payroll costs to keep up with industry in order to hire and retain skilled professors, but the people they're employing aren't suddenly more efficient at teaching. Class sizes stay the same but cost more per head, or else class sizes raise and quality declines.
The root cause is an unequal application of technology. In industry, an engineer can oversee design aided by computers, simulations, robotics... in general, lots and lots of automation, which lets them spend most of their time actively applying their training to the most difficult problems. In many classrooms, by contrast, professors and teachers still have to grade written test answers by hand. Until the education field picks up technology to the point that the teachers can spend a minimal amount of time on manual work, their pay is going to continue to outgrow their effectiveness, and school costs will keep increasing.