If it's an empirically true statement, how is it racist? I don't get it - she even seems annoyed by the fact.If she had followed up with something like "what can we do to help them or change this situation" that would have maybe been okay, but she said something like "it drives me crazy, some of them are good but usually they're just plain at the bottom". So it seemed more like she was just complaining about black people being at the bottom rather than trying to figure out how to solve the problem constructively.
It was an offhand conversation with a coworker that she didn't know was being recorded, she wasn't giving a speech. How much do you want people to self-policing their own speech that they believe to be private?