The thing that makes me angriest as an educator is that it's not so much a "failure" (implies accidental omission) as it is a tactical move to keep students ignorant of our history. Texas & Florida, noted for "anti-woke" stances, dominate a big part of the textbook market & determine content.

California is the other big driver, which is why a lot of textbooks have "California editions." Underfunded school districts buy secondhand curriculum from these two markets, which determines what their students will learn. So Texas & Florida end up having outsized influence on national education.

Saw a meme that said that history repeats itself and people ban history books because they want it to.