I'm not going to chase after the customers who forgot their wallets, sunglasses, and keys in the restaurant after they tipped me badly.
What do you think is going to happen now?
I might lose people's respect and I might lose my employment that way.
Although it's rude of them to undertip you, you should give them back their things. Those things are their personal property.
What are you talking about? Those people aren't coming back here. I am keeping their stuff.
If you have their wallet you should be able to find their address and give their stuff back. I know it's upsetting when you get a bad tip but you have to be the bigger person.