Another tipping question: counter service

I usually just tip a couple of dollars at counter service and window pick-up type places.

However, I recently ate at DiMartino's in Covington where you order at a counter, but the food is brought to your table, they pour your beer at your table, and bus the table as you eat. The dining room was also much nicer than typical counter-service places.

I had tipped a few dollars at the counter, but was not expecting as much table service and didn't have any cash to leave on the table as an extra tip.

I guess my question is: how would you tip in this kind of establishment? Considering the level of service, I don't really understand why they would opt for a counter over waitstaff.