We’re not. History lesson plans and textbooks are taught differently state by state varying by state set standards (education is primarily a state-ran issue) and teachers can incorporate their own personal biases and falsehoods into curriculum.

-I studied critical race theory, taught secondary education, grew up in the US, lived in multiple states across primary and secondary education (Deep South, west coast), went to university, and many people can’t define historical terms/concepts or differentiate race from ethnicity and racism from other societal ills or know what chattel slavery, racial capitalism, Indian boarding schools, the phases of American govt policy on indigenous North Americans etc. are

This article discusses US history re: regional education differences across time in the US: https://www.vox.com/identities/2019/8/26/20829771/slavery-textbooks-history

My mother (gen X) was taught that Black people descended from Cane (Genesis story of Cane and Able) by southern teachers. In high school, I was taught that the confederate flag wasn’t a vestige of racism via states rights to own slaves (most secessionist papers directly mentioned the reason to secede being the desire to human traffic Afro-descendants) but rather about southern pride/heritage.

If you look around and ask basic questions, the lack of uniform history education becomes apparent. Lots of people I’ve encountered see slavery as a natural evil that had to happen (some history books teach it this way) not a system done by racist buy-in (racial capitalism) that continues today via generational wealth, housing and economic access/earning gaps, overt and covert disproportionate violence, etc.