Couple of items I’ve noticed and seen happen.
1) restaurants will the tip amount to the bill and base it the price including the tax. Which it shouldn’t.
2) The tip will be added to the bill and then they will add a line asking for a tip and will end up doubling the tip.
The 6.83 that CT talks about is a little ridiculous. A waiter in a nice restaurant serving several tables can ultimately make more than $75 an hour and quite possibly a lot more.
I just saw a Baal Simcha give out $200 tips to each waiter. And this was at a Simcha where the waiters are paid 15-18 an hour.