I’m from the UK. As a rule we don’t have a tipping culture though I do tip if the service is good. I’m currently travelling around the USA and the service is terrible in most places I have visited- way below what I would expect in the UK. I would complain tbh if I received this service in the UK and yet there is an expectation of a tip at the end. 20% really? The entitlement has diminished the service.