Society says we should tip waiters and waitresses in restaurants - but is that right?

Restaurants are run on the effort of poorly paid staff putting in many hours. Tipping is a convention that has arised over time which makes it possible for those staff members to increase their take home pay through customers leaving money in addition to the cost of the meal and drinks expressing their satisfaction with their experience of eating, drinking, and service. Figures from 2012 suggest that tipping in London averages 11.8%, in Toronto 17.1%, and in New York 19.1%. If the figures were based purely on cost of living then New York and London should be pretty much equal given the expense of both cities. Personally, I favour tipping when I've had a good experience, and not when I've had a bad one - I don't believe it should be automatic. Even when tips are made, it's up to the establishment whether they're received by staff - some places don't allow them to be kept by employees. I like the idea that I can directely reward the people who contribute to me having a good experience, and don't think it's fair when management pools tips.