Now you can assume, if you'd like, that it's because the people in those fields are less-likely to be bad at their job, but more likely it's because they don't get fired because it's too much work to replace them, even if they're bad. There's as much of a nursing and doctor shortage as there is a teaching shortage, but because they're not government jobs (yet), we let the market take care of it, and it does so by paying them 6 figures.