Most white people don't know any Black people
More than 70% of white Americans have social networks that are entirely white.
Combine this with the fact that most Black people live in the South, and it’s easy to understand how lots of voices in the conversation around whiteness sound … uninformed. They literally have no experience around nonwhite people.
(Of course, the social network study leans on a survey methodology that might be flawed, and most research findings are false anyway. But this conclusion aligns with my own personal experience, so I buy it.)