It's not because I have money. I live in a tiny old trailer in the middle of nowhere. I don't have an oven or stove. I bake in a small convection toaster oven and I cook on hot plates.
It's not only when I have a great server either. If anything, I tip well especially when I have bad service. And it really irks me when people say stuff like, "I'm only leaving a tiny tip because our server was so bad."
See, my thinking is that servers usually have a sucky job with sucky pay where they have to suck up to people for tips. And sometimes someone just might be having a really shitty day, which naturally might affect their performance.
Imagine what a difference it would make to receive a generous tip. It might be the thing that turns their whole outlook around. It might change how they do their job. It might completely make their day or even week.
Some people may argue that if it's someone's job to serve, they should be expected to do it and do it well. The whole if I don't do MY job, I'll get fired so why should I cut anyone else any slack?
You should do so simply because you're a decent human being. If you don't do anything to help bring about a change, nothing will change.
In a somewhat related note, I was reminded of a "Louie" episode today where Louis CK has a talk with his daughter.
He tells her, "The only time you should look into your neighbor's bowl is to make sure they have enough. You don't look in your neighbor's bowl to see if you have as much as them."
We should really treat each other better.