Why is society even encouraging this kind of self-hostility.
The only self-hostility is those who are intolerant of diversity. Racists and other bigots are typical of persons who are self-loathing. The interesting thing is many of these folks are Christian, and taught to "love others as thyself". If a person loathes themselves they will naturally follow Jesus and loathe others. Jesus makes an assumption that all people love themselves, and it isn't the case with the intolerant.
My view is, in general, you are born with one of two types of genetic equipment. Use that equipment!
That works if we humans were machines. Our lives involve a lot more than just sex and reproducing. You seem to prefer a more black and white world that allows less fluidity in terms of personal meaning. We humans are often applauded for our creativity and openness, yet there are some people who want to limit openness to diversity and need more consistency around them. This suggests the problem is with them, and not those who may have been born with certain sex organs but are uncomfortable being defined by those biological features.
I am male. I'm completely heterosexual. I am comfortable in that. I am also comfortable with others being gay, or transgender. I don't understand their experiences, but I understand I have no insecurities that I need to impose onto these categories of people. Do you? It seems your position on this matter is about you and your discomfort, not others. Maybe you have doubts about who you are and instead of facing those uncertainies you recoil in denial and attack others who can face their experiences.
Coveting what others have is against one of the Ten Commandments.
Trans people are comfortable, you don't seem to be.
Why is this even an issue? Do teachers have so little to do that they need this add-on?
Teachers have to work in an environment with many more options of freedom, but also with many more parents who are hostile to change and diversity, and even who are violent. There are many issues that we expect teachers to deal with and still perform at a high level of expection. No wonder there has been a struggle to find teachers willing to put up with all this stress and turmoil in a society growing less tolerant and more violent.