As a white male, it is easy to make the assumption that everyone is treated the same as me; or that when they are not, it is a momentary lapse of service. However I have talked enough to friends and colleagues who are not white men and they (universally) tell me that they experience lower levels of service. One exchange that particularly struck me was a middle-aged Pakistani male colleague in London who asked me how often I got pulled over by the police. I said it had happened once when I was speeding. He told me this was a regular occurrence for him on suspicion of being a black man driving a car.
My guess is that the OP was slighted on the flight and that this is not his first experience of inferior treatment. I can understand the white man response of saying he could/should have raised it with the in-flight supervisor but I could equally understand that he is weary of having to demand equal treatment and sometimes it is easier to not cause a fuss and vent later in a more anonymous way.
FWIW, I am grateful to anyone who tells me that I might have treated them unfavourably as a result of my prejudice - it helps me be more aware of my prejudices ad the situations when they may cause me to make poor decisions. But I also know that they shouldn't have to do so and they have no obligation to turn my own poor conduct into a development opportunity for me.