Australia

i don't know how things are in Australia, but i do know how misogyny is so common in American schools. you can't think of it as being individual failures on behalf of the teachers. you have to think of this as entire system of patriarchy that selects for individuals who are less likely to resist it.

firstly are the weed out systems:

1. a school teacher needs 4-6 years worth of higher education to be eligible to teach meaning a school teacher is more likely to come from a wealthier, more conservative background
2. a school teacher is paid poverty wages, making them more reliant on spousal support, creating a soft reinforcement of traditional gender roles
3. teachers are hired by administrators who are usually men, men who can have unaudited privilege in the system of patriarchy, creating bias in what they consider "professional" for a teacher towards someone who will fit into this overall system

then there's the reinforcement systems

1. you are genuinely correct that most teachers are more progressive when it comes to social issues, but they are also making poverty wages meaning they're more reliant on the job. they're more desperate and therefore less likely to upset the apple cart
2. teachers are not the only people who interact with kids. administrators are usually who operate the punishment system in a school. this punishment system creates an interplay between the nurturing mother stock character and the disciplinary father stock character. the disciplinary father stock character in his role will often hand children mysogynistic views very directly.