I wouldn't tip for what I didn't buy. How ridiculous is that? The bar was full so you took a table. If there isn't a "food service at tables during lunch hours" policy then you've done nothing but create your own guilt. Tipping is so out of control is the US it's not even funny. The way you make more as a server is to work in more upscale restaurants where you are turning $500 or more in meals per hour. I'll tip 15% to 20%, and even tip a buck or two on a $10 buffet for someone to bring me a soda that if I'm in 7-11 I can pour myself.

Out of control.