Steph, to me, your friend who doesnt tip has no character. As for me, I ALWAYS tip. My grandfather taught me years ago that the servers depend on tips. Also, while I've never had a food server's paying job, I was a waiter in camp for several summers, and had to serve three meals a day, to two different halves of the camp, to several hundred people, so I know a bit of how hard carrying and serving food is.
As for my tipping habits, I rarely go to expensive places, but my rule is usually to tip about 18% on most bills, figuring to split the difference on the rule of 15% in average places, and 20% in good places. I will tip 20% or even a bit more on the rare occasions I do go to a nice place, and only if I have really bad service or a rude waiter will I tip 15%
I have a friend like your friend Steph. A few weeks ago we went to lunch at Kalhoun's, which is like a bar and grill, and we had a bad and somewhat rude waitress. He infuriated me by first getting into it with her, and then leaving no tip. She was not a good waitress, so I just left 15%. It also angered me what my friend did, because this is a place I go to all the time, and they know me, so not to tip is embarrassing.
I cant stand people who dont tip. To me, that is condescending, and rude. I find it embarrassing. I will say that I've been to the Bahamas a couple of times many years ago, and I do know that down there at that time the bill in every place we ate at had a 15% service charge for the server, because the service was REALLY bad, and they figured no one would tip. Even without that charge, I would have left the 15% anyway, because I know that being a food server isnt easy.
Mitch