You don't understand the non-pushback because you're someone who thinks of racism as a personal matter and something a person either is or isn't. Everyone is racist, I'm racist. Those ideas have been deeply ingrained into me from when I was a little girl all the way through now and they're never going away. What I can do is learn to recognize when my "first thought" is likely a racist one, push it to the frontal cortex for rational analysis, and adjust my response if necessary.

Racist as a pejorative is one who is doing it on purpose or with indifference, context matters. We perceive white children as smarter is an everyone problem, not an individual teacher problem.