It's almost entirely due to the fact that this is a profession that has traditionally been dominated by women, with a history steeped in subservient behavior. The majority of nurses practicing today are over the age of 45, and thinking about winding down their careers; young, intelligent women of today have far more career choices than women of 25-30 years ago. In economic hard times, people are quite willing to go to nursing school, but as soon as the economy turns around, they leave the profession in masses. Thus, nursing shortages are cyclical. It's just that this shortage is predicted to last a long time.

Right now, the shortage is about selling young people to become nurses.