I get where you're going with this but this explanation of TIW never makes sense to me. You're tipping whether you have TIW or not so you're till saving the 20% off your meal. Most people tip 18%+ anyway. I mean, I guess if you're a 10% tipper you're paying a bit more but I think that only applies to a very very small number of people. You're stI'll saving off your out of pocket regardless of whether you call it the tip, meal, whatever.