> Curricula is set by politics and ideology, not established science.

This is part of it. A friend is a teacher and is now in an admin position where he manages teachers. His big gripe is the higher ups have no formal system - every time a new person comes in they bring with them their system and politics, burning down the previous efforts while doing little to nothing for students. Then they leave for greener pastures and the next ideologue comes along with their matches.