I think the disadvantage part is that to be a good teacher one needs to at the start of the teaching career to devote very long hours that aren't so easy to find once you have children. If you are a teacher first for a number of years, then have kids, I think it works more smoothly. I suspect many women are afraid to take the risk of the low paying career at time in their lives when they don't yet have the guarantee of the second higher-paying career because they haven't met or married the guy who will supply it yet because they are still in college. As the child of a life-long teacher I remember calling her at 5 and 6 PM when I was in middle and high school to see when she was coming home. Good teaching is not 7AM-3PM, it is 6:30 AM-5:30PM minimum. On the other hand, the summers at the pool with my mother were glorious.