Even Black staff do not want to wait on Black customers. For so many examples the Black customers have numerous requests for additional service, always additional attention...And so many, many times resulting in no tip.
Stereotypes have their 'birth' because of a cultural behavior, common experience of different races/genders/ages/religions/ethnics.
In the premise set forth in this article IMHO...this couple has a chip on their shoulder, discerns injustices all around their lives. One cannot really 'win' with a couple as depicted, just provide great service, expect nothing and roll over to the next seating.
LaBron James is well known for this type of behavior!