The vast majority of teachers are liberal Trump-hating democrats.
That is the opinion teachers are supposed to have. The Huff Po expect that of them. The Teacher's Union leadership expects that of them.
The Left is an anti-intellectual hive-mind. The individual is considered "smart" or "woke" and even presumably "intellectual" when they go along. That is why they go ballistic when somebody attacks the hive-thinking. But not all the bees are infected with the disease, an unknown number of teachers have anti-hive opinions, but they can sense that they will be punished if they rock the boat.
The Left makes examples of people. Like Brenden Eich at Mozzila, or more recently James Damore from Google. And of course the big one they are trying to fire for exposing their B.S. is Trump. That is why the fact that the country is actually doing well does not matter to these people. He is primarily guilty of a thought crime.