City Cafe - Dont eat there if you dont have money

I mean literally you have to have SOME money to eat there..

Last night my fiance and I went and ate at City Cafe. Decent food and there wasnt as much a wait as other restaurants we went too plus decent charbroiled oysters.... Well we sat down and I immediately noticed this one guy wearing a muscle shirt. (Who does that?) The place isnt really dressy but c'mon.. After they got their check they looked lost. So the guy got up and left and was gone for like 15 min. I went on eating but the girl just sat there calling people on her blackberry. Thought he left her with the check for a while. Finally he cam back and they started fighting a bit.. The guy threw some money down on the check tray, never signaled the waitress and walked out rather fast. Bus boy cleared the table and Im thinking this whole time that they either stiffed the waitress or stiffed the waitress and the restaurant. finally the waitress came to check on them and was a bit suprised they had left. Looked at the money and the bill and mumbled shite there was two bills at least but obviously didnt cover something. Who goes into a decent restaurant without money to pay for the meal? So does the waitress have to eat the difference? How does that work?