Because white is not a race, it’s used as a counterculture to the use of Black (previously also Negro and Afro), and historical evidence supports that. “Black” is only used as an identifier by that ethic group and their erasure of ethic identity. While African American is another term, within the culture of the of the group, it’s lacking once more an actual origin and lumps those who do actually know their African origins with those who don’t, leading to the premise of the self-codified ethic term Black. This term has been preferred by the National Association of Black Journalist since 2017 and was picked up by major newspapers and the AP only last year.