“There is one gender that are terrible tippers.”
That would be my gender. I think that separates out in to two groups: Those who have been waitresses at one time (me) tip very well. Those who haven’t had that job are pretty bad. Generalities, of course.
I would generally agree with your exception. I think duration of being a waiter/waitress has an impact on how someone tips as well.
When I was a waitress I don’t remember having a huge problem with females not tipping.