And there was me, a poor simple minded Brit, who thought that the brochures all said that the following amount is the RECOMMENDED tip/gratuity. Unless US dictionaries vary totally from Oxford English recommended does not mean compulsory or to be exceeded. It is a suggestion and at the discretion of the giver. If you want to make it compulsory at a set rate then say so and don't expect me to pay anything over the odds! "Should have tipped more initially" is totally out of order. "Should have tipped less after that reaction" is far more realistic.
See you in camp. Paul