Relative to the number of people and stressful situations the job has to deal with. Keeping a roomful of kids focused while dealing with all of their individual needs and the inevitable chaos that ensues with kids is just as difficult as what a construction foreman does, dealing with workers and contractors and bosses. But the construction foreman's work is considered more valuable and therefore he's paid more. Taking care of kids and the sick and elderly has always been considered non-skilled women's work.