I've recently been reading/watching some videos and writings by Robin Diangelo on systemic racism - here's a great starting point: https://www.youtube.com/watch?v=h7mzj0cVL0Q. She also wrote the book "White Fragility".
Thinking about that, I'm just wondering how different it would be if one of those people who mistook the employee for the CEO instead turned to the CEO and said "I'm sorry, please excuse me for the instance of racism I just perpetrated against you, I promise it won't happen again." I realize how outlandish that may sound writing that out, but I'd propose that the fact that it does sound outlandish is the main problem. Everyone in the US was raised in an environment that inculcated certain racial ideas, subconsciously or not. We can't address them if we're so embarrassed by their existence as to pretend they don't exist.
Racism doesn't imply intent either. It absolutely can be the case that someone unknowingly makes a racist inference even with the best of intentions.
It is not racist to assume that the person in the room most like the other CEOs you have met, is also the CEO. If I was in a foreign country, I would assume the CEO is the person most like the other people in that country. I never made any assumption about competence. Half the time I think the least competent person in the room is the CEO. Sadly that's how business works. There would be nothing racist - intentional, or unintentional - about my assumption.