Nettie1964, the staff have to buy their own food? 
No, not really. Do you know that most people have to do that? Every day?
A waiter or waitress is supposed to do their job well. A really good one is still doing that same job. There is a limit on what they can offer doing the job, there isn't much scope to increase wages, not without promotion/change of job. That's what everybody else has to do.
I'm getting a bit fed up with the 'poor waitress' syndrome that's cascading down the thread. I visit the same restaurants often, get excellent service - and tip really well. I'm not going to do that in a restaurant where somebody is merely doing their job because largely, there's nothing remarkable about it.
To be quite frank there are a lot of other occupations that deserve tipping - and can't receive them.
Just as an aside, hotel breakfast staff - usually brilliantly efficient and I'd tip them.. but they can't have tips. Pitch up for dinner and they feel entitled. It's really annoying and often they can't compare to the excellent breakfast staff.
I tip hairdresers too - and hairwashers - but not the hairwasher yesterday, she was dreadful. No tip.
So, if you like to chortle in the kitchen and bitch about your customers, knock yourselves out.