Single-payer, compulsory-funded, compulsory-use, and socialist-entitlement schooling has **always** been run by liberals. It was a Prog idea in the 1800s. Progs have always controlled teacher training and curriculum development. The Progs have always been pushing the envelope of society's morals and ethics.
Fundamentally, SS schooling ( single-payer and socialist-entitlement schooling) can not be fixed precisely because it is built upon a foundation of socialism! In just one to three generations of SS schooling the nation voted in Franklin D. Roosevelt!
Nearly every teacher in this nation ( even in private schools) was trained by godless Marxists in Marxist-run colleges and universities. Even if the teacher is not a Marxist, the training does leak through into the godless classroom.
Also....Please remember that government K-12 schooling was the nation's first single-payer and socialist-entitlement program. At its best it was merely generically lukewarm in its Protestant worldview. Since the 1960s they have been utterly godless.
It was largely a scheme to turn Catholic kids into protestants.