” . . . family get up without tipping and then remove tips from two different tables as they left.”
I have observed the lifting of tips from tables as well. At certain restaurants, where I have concern the waiter or waitress will not receive my gratuity, I hand the waiter the tip or pay the check with a credit card and include the tip on the charge. When the service has been outstanding I hand the server a tip of at least 20%.
If the tip is on a credit card then it will be recorded for tax purposes so when I have concerns I will shake hands at the end and pass the money that way. I will tell them that I just want to make sure they get the tip and not someone else.