Well, I think people have to decide for themselves. If you accuse someone of bias without sufficient evidence, there’s no reason you should be believed. As for most instances of racism merely being bias, I don’t think this is the case, at least for allegations that make it into the NYT. Typically there is also evidence of a hostile environment provided. When there isn’t then the evidence of bias needs to speak for itself.
(I edited a second half into my original comment that might make this clearer, though I did that before I saw your reply)