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.
It means your behaviour is informed by racial profiling of an individual.
It means that you're not treating someone as an individual, but rather based on membership of a racial group he happens to be born in, which has statistical characteristics (e.g. lower chance of being a CEO) that do not necessarily have any bearing on the individual at all.
We define treating people distinctly like that because of their racial membership, as racist. That's really just the definition. You can have a discussion about whether you think racism is justified or not, and make your own value judgement. You could say that even if membership of a group does not necessarily say something, odds are that it can be a good way to infer things. And that's true, group-membership (e.g. your ethnicity) has many useful correlations from which to infer things. But to say it's not racist simply isn't factual, it is racist according to how we define it. What's left open for discussion is whether racism is okay or not.
Of course as a society we have indeed had that discussion and fortunately decided that racism isn't justified, not okay, and should be prevented as much as possible. I'm happy about that. Because even if group membership (e.g. race, ethnicity, gender, sexual preference, religion etc) has correlations with all kinds of outcomes we may wish to approximate, as a society we agree that it is only fair to judge people on their individual merits, and not on the group that they belong to.