My wife has said the same. Also older white people with money (country club types/ lower/ high society types) don't tip very well either.
Servers treat young people different too, for the same reason that they're perceived as poor tippers.
Just as wrong or no?
Now the guys who own things like Murphy farms and stuff like that are more down to earth and tip well.
There is a line of perception across a few different fields. They are blurry because of the exception to rules type, but they are there none the less