It's cheap to not tip.
Francis is going out to eat with friends, knowing that his rent is due the next day.
Francis wants to save money on dinner.
Francis orders a value-meal, leaving enough in his budget to tip.
Francis orders a large steak and decides to save money by foregoing the waiter's tip.
Francis' waiter is paid, and Francis makes rent the next day.
The waiter works all day and goes home without the appropriate compensation.