Some people actually do not have any shame....they leave the table a mess, make demands on the waitress, even tho' she takes the time to get their order right. Perhaps those who do not tip, think of the waitress as a "maid".....
Even at home, I take the time to cook a good, nutritious meal. And all I expect from my boys is "Thank you, Mom"...and they help clear the table, and take their dishes to the dishwasher....I'm not their "maid" or even their waitress.
We always tip the waitress and even say "Thank You".....and I do know how hard those waitresses work, as my mother was one. She supported 6 kids, worked 2-3 waitress jobs, and those tips paid our rent. Her legs were really bad, varicouse veins broken in so many places for having to be on her feet for hours and hours.
Perhaps those who refuse to tip....should work several days as a waitress....get the first-hand knowledge as to how hard it is!.....It's more than just taking an order and bringing the food to the table. And for those deafies that do receive SSI or whatever, all they have to do is sit on their arse....at least these waitress/waiters are working.