Wait staff love tips because it gets them paid significantly more than if they worked a retail job.
After visiting Europe, tips are necessary for good service. The rudeness and lack of service was culture shock.
There is a stereotype that blacks are worse tippers than whites. As https://www.ebony.com/news-views/are-black-people-really-bad... comments, it might be because blacks have "Insufficient education about tipping", or "a loop of circular behavior where Blacks have been traditionally discriminated against, Blacks expect to be treated poorly and treat servers with disdain, servers treat Black patrons with less care because they “know” Blacks tip poorly, and Blacks continue to tip poorly because they continue to get substandard service." (there are a couple of other proposed reasons).
See for example http://www.tippingresearch.com/uploads/JFSBR_race_revision_a... which includes the quote “I will not take Black tables unless I have no other option; call me racist, but I also walk out with more money than the people who end up with them.”
Yes, if you are a black American, you might get rudeness and lack of service in service in your own country - because wait staff think you won't tip well.
Over here, more than a single interruption ("is everything OK?") is intrusive. Fake smiles and fake enthusiasm aren't desirable either.
All Europe was like this?