When my son waited tables at Applebee’s, his comments about non-optimal tips from that group as being just the way they rolled and there was no connection he could discern to any other factor.
Actually there is more to it than that. That group, or within that subculture,usually the ghettoized lower class ones, as another commenter posted they will play games with the waiter/bartender and its a game for them all.
They’ll ask for the ketchup, you get the ketchup, then immediately they want the A1 sauce, you get that, then they want a toothpick or ‘whatever they can think of that you have’. They will run you! and you are running back and forth from their table. Frequently as part of the game,at the end of the night at or near payment time, they will complain also about something, their food or drink. And guaranteed these people will leave Zero tip. And its all their game on you!