“The problem is that that situation existed because of real sexism - a level of discrimination not acceptable.”
Not only was it acceptable, it was essential, as we see from the mess around us.
We had better get back to that ASAP if we are to survive as a civilization.
Besides the remedy is easy - pay more. Make teaching ‘full time’, eight hours a day, all year long.
If you pay a highly competitive wage, make it a year long job (NOT a nine month sinecure) - you'll get plenty of high quality people. Oh, and outlaw ‘education’ majors... except for elementary school teachers.