If I may, I have some thoughts. I'm mixed as you may or may not know. My dad was Black. My mom was white. I'm white presenting. I have a sort of unique, both sides of the coin perspective on race. I've asked this question many times. The answer is always the same, whether articulated as such or not...fear.

Some fear that acknowledging racism will lead to something being taken from them, their jobs, their homes, their money, etc. They seriously think that acknowledging the problem may lead to people of colour showing up at their door looking for recompense (figuratively). Those who have enjoyed a privileged position are loathe to give it up. There's no incentive to acknowledge a problem when it's not a problem for you.

Then there's fear of responsibility. To acknowledge is to admit a problem. What's the next step? Do something. Well.... That's when you hear the, "It was a long time ago, I don't keep slaves," narrative.

I'll stop here, because I've gone on way too long for a comment...