
Well mathematically, black people are only 13% of the population, so unless they are intentionally only dating within their own race, there are a lot more non-black women for them to potentially date than black women. White women still constitute the majority of American women, so in a purely random distribution you would expect to see most black men have a white woman for a partner.
I mean that wasn’t actually in OP’s question. But also I’m not sure it’s actually lower, I think there’s just less attention on them. Because ‘black men with white women’ commentary often comes with the connotation of ‘they’re stealing our women’, whereas white men with black women rarely get discussed in the same way.