[Bystander22]

I think the tip jars are a scam, but tipping waitstaff is important. However: Tip waitstaff with cash because their wage is much lower than most tip-jar situations.

Restaurants pay workers the minimum wage for tipped workers ($2.13/hour in most states), but must make up the difference if the worker's wage plus tips don't equal the minimum wage ($7.25 in most states).

When I waited tables, we were forced to turn out our pockets at the end of a shift and count out our tips in front of the boss. A lot of us took cash tips and stuffed them in our shoes beforehand.

Plus waitstaff had to pay for the credit card charge (2% at that time for MasterCard and Visa) if someone charged their meal, so reducing that as much as possible was helpful.