This has nothing to do with unions or not and hiring more workers does not automatically lead to lower salaries. You're just making stuff up now...
"From high schools that don’t promote the trades and working with your hands as anything but a last resort to apprenticeships that discriminate, to jobs websites that always advertise using gendered phrases (e.g. “looking for handy guys to join the team”), these are all things that women face when looking to get into the trades.
https://www.nytimes.com/2018/02/08/sunday-review/sexual-harassment-masculine-jobs.html#:~:text=Insults%2C%20groping%20—%20even%20assault.,countless%20women%2C%20to%20be%20intractable
"Insults, groping — even assault. That kind of sexual harassment came along with being one of the very few women on a construction site, in a mine, or in a shipyard. Those professions remain male-dominated and the harassment can seem, for countless women, to be intractable.
As Christine Williams, a professor of sociology at the University of Texas at Austin, pungently put it, women in so-called men’s jobs are labeled either “sluts or dykes,” each abused in their own ways. Although statistics are spotty, some studies have concluded that sexual harassment is more regular and severe in traditionally male occupations. And a Times Upshot analysis of blue-collar occupations showed that women’s presence in these jobs stayed static or shrank between 2000 and 2016.
“Sexual harassment is often a way in which the men reaffirm women’s femininity, say this is who you are, back in your place,” Professor Saguy said."
You know what happens when women enter into formerly "male" professions? The salary and prestige of that profession plummets.
"She is a co-author of one of the most comprehensive studies of the phenomenon, using United States census data from 1950 to 2000, when the share of women increased in many jobs. The study, which she conducted with Asaf Levanon, of the University of Haifa in Israel, and Paul Allison of the University of Pennsylvania, found that when women moved into occupations in large numbers, those jobs began paying less even after controlling for education, work experience, skills, race and geography.
The reverse was true when a job attracted more men. Computer programming, for instance, used to be a relatively menial role done by women. But when male programmers began to outnumber female ones, the job began paying more and gained prestige."
But women did not "force" their way into teaching. As if women in the late 1800s had any sort of power whatsoever. Give me a break....
"The feminization of teaching must be understood in the evolving context of American education. In colonial America, most young people learned necessary life skills from their parents or as part of an apprenticeship. The ability to read the Bible was valued. Teaching at that time was an occupation for young, white, well-educated men. Teaching was a part-time occupation, done mostly in non-farming months, or as a precursor to a full-time career for pre-professional men. In the 1800s, there was a movement towards universal education and a formalization of the once-informal education process, creating new educational roles such as principals, superintendents, and educational experts. All of these were predominantly male, though educational decisions were implemented by an increasingly female teaching force.
Industrialization, the availability of other jobs, and the perception of education affected the degree to which teaching became feminized. The industrial revolution created a wide variety of jobs for men; many of these jobs paid more than teaching."
So, this has been real, but I honestly don't have anymore time to swat down your unsupported assumptions with facts, statistics, and reality. 👋