That's because even in the rich white classrooms, it's not about teaching actual history. It's about selling a narrative where America is the good guy, the very best, so that they can create "patriotism," which then goes on to create good, loyal workers and soldiers for the rich to exploit until they've outlived their usefulness. And, it serves the added bonus of convincing those sociopaths who will go on to hoard wealth and become part of the next generation of exploiters, that they're privilege is actually divinely ordained birthright.