"In Mexico you basically only have one race so it is not a good camparison."
The other really bad tippers(stiffs) from the late 70s and early 80s were from San Jose, California, Australia and Japan. The Australians and Japanese had just finished an 18-hour flight, so they may have had an excuse.
Still looked like geography instead of race to me, but it may have also been a nature vs. nurture issue.
Never could figure out this inverse ratio, though: People that made you work your butt off threw nickels around like manhole covers, while ones that didn’t require much more than conversation were extravagant.