I have a personal rule: I don’t go out to eat (at an establishment) unless I’m prepared to tip 20% of my bill for the service.
Sometimes I’ll eat with a group and it never fails that one in a group of four or more will skate on the tipand sometimes the tax if they can get away with it. A few rare birds I’ve seen will even try to slide on the drink. And these are folks that I know can cover it.
It doesn’t surprise me that establishments will put an automatic 15% gratuity on parties of 5 or 6 or more.
Sucky thing about that is I have to be careful, I have four kids and there has been more then one occasion that I have had a gratuity automatically added to my bill, then left a tip on top of that. Usually it has been for crappy service, when the server feared getting a lousy tip. I will tip better for good service then bad, but I will still tip for bad service, it will however noticeably not be as generous.
I had a server confront me one day about a less then generous tip, I told if she had done a better job she would have received a better tip. My next trip there I had outstanding service from the same girl, I more then made up for the previous visit.