Although I do agree that tipping should be voluntary and based on the level of service received, I must admit that I find the attitudes of some posters toward working people in this thread obnoxiously ignorant and appalling.
Many people are dependent on tips. Here in the United States, the minimum wage for tipped employees is somewhere around $2.00 (give or take a few cents). That is not enough to buy a pot to piss in, especially if you work at a restaurant that is not very busy. On top of that, a tipped employee is responsible for paying for rent, transportation, health insurance and health-care-related expenses, childcare, etc.
Think about that. If you're so bent out of shape about tipping, why don't you lobby for higher prices so working people can be paid a living wage. That way, you'll never have to worry about grubby poor people extending their calloused hands for "handouts."