Originally Posted by
nkedel
Good for them.
At least some of the local places in SFO do; the counter-service hamburger place "Burger Joynt" (T2 and International, not sure about other terminals) will even print a tip line on the charge slip. What service they're expecting one to tip for, I'm not sure.
That being said, I wouldn't support them as I would typically eat at a lounge or onboard.