Why are women not going into S.T.E.M fields as much as men.

We always here that women only make 75% of what men make, but they only work about 50%
of the jobs that men do. Not only STEM, but also no women are working in sewers, oil rigs, etc.
these are high paying jobs. Also women are less likely to move for a job, and they are less
likely to work outside. Why do women not want to be equal to men?