Tipping is not optional. Waiters are paid well below minimum wage and expected to make up the rest in tips. If you don't have the money to tip you don't have the money to go out to eat.
This is what I don't like about tipping. "you HAVE to tip". No, I don't. If I don't have enough money to tip that doesn't mean I shouldn't stop myself going out to eat.
Sure, it's not nice that these people have a crappy job, but it shouldn't stop you from doing things just because they don't get paid very much. "You're not allowed to enjoy your own money because these people don't get much money". Really, at what point is that your problem?
In the UK we have laws for minimum wage, so the fact that 'tipping' has made its way over here really bugs the crap out of me since it's essentially a redundant thing for us to do. It's not as widespread as it is in the US but it is becoming more and more common.
It's just annoying that we have it since waiters will be earning (by law) the same as people such as some manual laborers, desk jobs, store workers etc so why should they have a tip? Somebody working in a busy office can't beg you for a tip, so why should a waiter in the UK when they get the same wage?
I've had a few places that have asked "will you be leaving a tip?" to which I just replied "I don't believe in tipping" and it was left as that. Most places leave it as an option at the end of a receipt or when you're paying with card, so I just ignore it.
I've had one person who's actually 'chased me' for a tip, to which I nearly punched him in the face.