I don't know about your public school
experience, but I was exposed to a ton of revisionist history and outright brainwashing. That was in Los Angeles in the early 1960s.
Early on, I was taught that Indians and Pilgrims were pals and had a great potluck at the first Thanksgiving, and that the commies (Cubans and Russians) were going to annihilate us any day with nuclear weapons. We were all made to crawl under our desks and curl up in a fetal ball on a weekly basis as practice for the nuclear attack. Now, that tactic has dubious value in protecting from a nuclear blast, but it's a great way to program small children to fear and hate. We were taught plenty of other stuff too that I found out many years later was less than factual, and were
never educated about some critical issues, but I won't belabor the point.
The point being that public education curricula, particularly the history and social studies components, often are designed not to make children well informed critical thinkers so much as easily manipulable, useful tools.
The Texas curriculum in my view is not an exception to the rule so much as an acute exacerbation of the pre-existing condition.