Well as a matter of fact, the colleges really can't get enough people to teach. This is why there is such movement towards online super-sized lectures: they want to teach an order of magnitude more people (charging them for the service).

The problem is that university administrations have tried to transform their institutions into profit-making businesses, and have insisted on cutting corners. They are hell-bent on the notion of teaching an order of magnitude more students without hiring any more tenure-track professors.