Sometimes it doesn't.

When I worked as a waitress for Red Lobster (college years), we got 100% of our tips from cash and charge, as the busfolks and bartenders got living wages (over $7 an hour), we got $2.01/hour.

However, I recall one restaurant my husband and I frequented, a chinese buffet near our house. We went there at least 3 times a month, sometimes more. We always paid with credit card and left the tip on the charge slip.

One night, we were there with friends. The waitress would refill their water, but ignore us. We asked why, and she said, angrily, that we never tip!

We told her we always tipped on the charge card, but she didn't believe us. We asked to speak to the manager, and the person at the front desk said he wasn't available. The front desk person (who I later found out WAS the manager) refused to answer our questions about tips left on chargecards. We told them that we would be letting all our friends know about their scam, left the waitress a $20 tip in cash, handed to her personally, and left.

My husband called his friend at the local paper.

A month later they were closed.

Quick karma is sometimes helped along by practical connections