It really helps to put yourself in the mindset of the typical tipper... these aren't millenials, these are boomers and many of them are europeans. They aren't familiar with the etiquette of dealing with people from different ethnicities simply because this topic entered mainstream conversation very recently. I am living in Europe now and I have a 45 year old neighbor and she was telling me how she had never seen a black person until she was 20 years old. Imagine that. So some of these tippers are men in their 40s, 50s, 60s, from very ethnically homogenic societies who ask this out of curiosity and also to show interest in the other person, just to make conversation, it never occurs to them that this could be rude or awkward at all.
And I will give you an example... I grew up in a community with very wealthy people and one of the things my grandpa taught me when I was just a kid is you never ask other people what they do for a living. This is because in affluent circles it's really rude and awkward to ask someone else this question. People in general tend to ask this question to others without thinking twice because /most/ people have a very homogenic circle of 9 to 5 workers or freelancers at most and you ask this out of curiosity or just to make conversation. But in affluent circles this is a question that makes everybody uncomfortable. Old money people don't work, they don't do anything "for a living" and now you put them in the uncomfortable position of having to come up with an occupation. Others have very non-traditional income that is difficult to exlpain in a social setting, and some will feel like you are asking this cause you want to get something out of them. A middle class person will have the best intentions when they ask a group of people what they do for a living without knowing they are irking TF out of everyone. Same thing with boomers in camrooms.