That I also understand and is a great tip in it's own right, thanks.
I think many of us tip because we're afraid not to. There was a guy I used to work with who totally changed my opinion on tipping and stopped me being afraid of saying no tip to poor service. He got into some right old fights with people who expected a tip, the worst being a taxi driver who took him from Las Vegas to the airport without saying a single word, then kicked off massively at the airport and threatened to drive away with his luggage unless he tipped.
From this thread I'll definitely look after the waiting staff but think that'll be it unfortunately.