It's at least refreshing to hear a non-US citizen endorsing the idea that it's not necessary to conform to the norms of the country one is visiting - that's a common criticism of American tourists.

We've spent a considerable amount of time in the UK, several European countries, and Australia over the past few years, and dined out a few hundred times in total. To generalize perhaps to an absurd degree, I suggest that visitors from those countries can add a modest 15% to the amount of their U.S. restaurant check/bill and still get as good a deal as they would dining at home, amending the fairly common waitstaff perception of the "ugly foreigner" while actually paying for the service rendered.

Just a thought...