listener, your whimsicality strikes me as "random acts of unkindness". If you want to overtip for coffee, please do. But the server who only gets $10 on a $100 meal is likely going to be splitting that tip with the maitre d', the bartender, and the bussers - which won't leave a lot left over for the server, will it? Not to mention wondering what they did wrong.

If you don't like the system, you're not alone - but 15% really is the expected minimum for any kind of reasonable service in US restaurants. We are certainly capable of not leaving any tip in the rare circumstance of really bad service, when we also explain to the management just why we're not tipping, but good service gets at least 20%. And you know, we usually get very good service, especially after our 2nd or 3rd visit to a place.