Is it not expected that when you pay money for a service then the performance should be good? Good service should be the default. If the service is outstanding then that is when we should start giving a bonus.
US tipping etiquette has nothing to do with good service and all to do with propping up underpaid staff.
I think we agree, it's more of a matter of adjective grade. I expect service to be adequate. Some of it is frankly good. Once in a while it's outstanding.
As for US tipping etiquette, cactus2093's point was that current US tipping doesn't really reflect what was originally intended. But kingkawn made a claim that extended past the current US tipping practices.
US tipping etiquette has nothing to do with good service and all to do with propping up underpaid staff.