Many of those jobs produce fewer tangible outputs, are government jobs, non-profit, or otherwise do not focus on maximizing profit. Positions like teachers, social workers, etc are seen as cost centers, not revenue centers. They are necessary jobs and perform valuable societal functions, but they are supported through other revenues which were not a direct product of their job. As for why one gender chooses those jobs more than others, there are a variety of factors. One of the leading ones is that some people are more likely to choose work that is meaningful over just a dollar amount. Studies show that isn't just based on gender, but also in the some minority groups.