If the industry were either actually or even merely perceived as systematically unfavorable to women, a natural consequence would be women being less likely to pursue education focussed on the field in preference to other fields that were less unfavorable.
There are many other factors that can come into play. It is simply incorrect to draw the conclusions you do.
One example is earning prospects, which might matter more for men than for women. Personally, I was torn between studying maths and film making, for example. I decided to go for maths because of the better money making prospects (I thought), thinking I could still go into film making later.
If you don't worry about income prospects, maybe you are more likely to choose English literature of the 16th century over engineering.
It's not. The CS graduation ratio is just as bad.