Actually, no, GP is right!

If they weren’t given an option to tip while paying with a card, plenty of people would pay with that card and then leave a cash tip in the tip jar at their favorite coffee shop (nobody is going to request that their card be run again for a tip). There are places that make you sign a receipt and add a tip—but that isn’t always part of the Square flow.

Now it’s integrated into the PoS system, so the default option is to give Square their cut for a tip.

Sure but not all of the money customers pay goes into expenses. Some of that is profit! So if workers stay because they make more money now that customers are voluntarily paying 20% more, you dont have to keep raising your wages. And wouldnt you believe it more of that customer money turns into profit!