However, right at the beginning, this is really a bad argument: “There is particular concern about the lack of women in prestigious STEM fields, such as Ph.D.-level faculty positions, but surprisingly there is no concern about the under-representation of women in lower-level technical jobs, such as car mechanics or plumbing.”
This can hardly be surprising to the authors. People in lower-level technical jobs don’t have as much power over society at large as those in high-level positions. Thus gender imbalances there don’t have the same supposed impact and perpetuating effect on structural imbalances as those in high-level fields (an example: the recent study about facial recognition being less accurate on female faces). Thus they are not considered as harmful in the grand scheme of things.
Edit: In other words: no matter where one stands in the debate about the reasons for gender imbalance in STEM, it is totally reasonable not to be too concerned about imbalances among plumbers or car mechanics, because this imbalance does have less consequences. It doesn’t matter for any other aspect in life whether a woman or man fixes the car, but it matters who creates the algorithms that control everyone’s lives.
Others have commented in this thread how gender-biased attitudes towards engineering fields are present even in young children. There's an obvious connection between this and the fact that when you're a child most of the adults you met in your everyday life practicing technical jobs (plumbers, cable technicians, car mechanics) are male. On the other hand, children see how their pre- and middle- school teachers are mostly female. Thus, children learn by observation that technical job => male.
Yes, neither car mechanics nor pre-school teachers have prestigious, 6-figure salary, PhD level positions, and yet they have a big impact in the perception of gender bias in adult labor when children are growing up and unconsciously cementing their views of the world.
I believe that a big step to close the gender gap in engineering would be young girls watching the super cool woman in the car shop expertly fixing daddy's car.
Can't wait for the next campaign to make men 50:50 in kindergardens and schools!