That just isn't how humans learn. You think you are teaching to not hate, but they learn that hate is normal. They want to be normal. You teach that diversity is important, but they learn that they are the undesirables or that they don't have to try in life. Just focusing on the differences puts them on different teams, and thus in opposition. It won't be otherwise.

We have seen what teaching people about this leads to, because we've been doing it for decades, and the result is not a lack of racism. You don't solve racial division with racial division.

Most of these efforts do shelter kids from history. Kids learn a false narrative that slavery was just evil white southerners enslaving black people. Nothing is said of the fact that the first slaveowner in the pre-USA colonies was a black person named Anthony Johnson, or that free blacks in the USA often owned slaves, or that black slaves were purchased from black people in Africa, or that the very term "slave" comes from the white Slavic people, or that black Africans are still being sold today, or that enslavement (generally, and particularly of black people) is endorsed by a major world religion.