I’m not disagreeing with your theory but I’d like to invite you to Canada to see if you observe the same behaviors. I know what you’re talking about and I always assumed it was American behavior. US citizens are spoiled with all their quality, customer service and they just keep asking for more. But you’re right, it’s mostly Americans of the white variety.
In Canada, I’ve worked with refugees and had immigrant friends whom I’ve counselled to “ask for more”. As newcomers seeking a better life, many new Canadians are so thankful for what they have, they are afraid to press on when things don’t go their way (e.g. an unfair landlord, someone pushing in front of them in line). Maybe that’s part of your theory too. Those who are used to power, used to getting what they want are NOT thankful and continue to demand more. Perhaps we (whites and other demand-y types) need to learn to be a bit more thankful and appreciative of what we have.