The study found that 143 colleges and universities are using some form of differential tuition, and that the number of schools adopting the model has grown every year since 1985. Universities say shrinking state budgets are to blame, forcing them to bump up charges for upperclassmen and those pursuing degrees — such as business, engineering, and nursing — that will lead to more lucrative jobs. Is differential tuition a fair policy?
Absolutely: Universities have to pay "competitive salaries to retain" professors who are in demand elsewhere, says The Cavalier Daily of the University of Virginia. The "market value" of business, engineering, and nursing professors is higher than that of other disciplines, and it makes sense for those programs to be more expensive. And while increased tuition would "dissuade people from low-income backgrounds" from entering those programs, "some of the additional money from differential tuition" could go toward financial aid packages. That way, "the costs and benefits weigh out."
another position at link.