You don’t need an expensive study for this. Just go to any nice restaurant and ask the waitstaff.
Both my daughter and my granddaughter (her niece) have worked/work at high-end places and they will both tell you the same thing.
Even the black waiters/waitresses didn’t want to wait on other blacks.
So post a sign on the door and menus that says all checks include a tip.-— period.
wife worked as a waitress , not a fancy place but a chain place and she said when they got groups of them in the wait staff never wanted to serve them because they would have you running about, make such a mess and they were so loud and obnoxious , even food on the floor, all over the place and many a time the other people would complain about the noise they made.
This is not just restaurants either but hotels, by the swimming pool, late at night , even in stores.
Not sure why they have to be so loud all the time especially when there are groups of black women
One solution: say "no tipping" on the menu, raise prices 15%, pay the waiters a salary.
Of course, those who refuse to tip would then refuse to pay the higher prices either, and just go to other places, and not tip there.