I’ve seen that first hand.
Large groups are the worst and I have seen waitresses reduced to tears by the abuse. The complaints about anything and looking for freebies were often.
The worst groups were black women. Just vicious. Managers were always getting involved as they would complain endlessly.
A club I used to frequent had the same problem but far worse. For some reason a large black professional group started going to this club right about when it would open and stay for a few hours. These were professional people and I think they gathered not long after work hours.
There were at least two hundred of them there at a time.
I knew the three bartenders quite well and they all said basically, the three of them worked for free when that group came in. They just didn’t tip. Or if there were tips it would be pocket change from the purchase of a drink.
I have no idea where this comes from but its true.
Same club would also attract any number of professional sports players on Boston teams. The man of the three bartenders I knew had to chase down a couple of players with the Boston Celtics after they just walked out on a check.
The guy said it happened more than a few times, The players claimed they thought everything was being comped for them. - and on top of it - a terrible tip would follow.
I was at a similar restaurant a couple years ago with a large group of mostly black people, and a server came out shortly after providing drinks and quietly handed each person a generous $3 off coupon.
Doubt I’d have gotten the same thing with a group of Caucasians.
I tipped based upon the original total, bet the server was happy with whatever he received from the other group members.