IMO restaurant tips (and other service businesses) are 15% by default, 20% if they do well, 10% if they do poorly. If they do especially poorly (like, completely ignoring the table for an hour while chatting with coworkers off to the side), they get $.02. If they do especially well, more than 20% (I've gone as high as 50% once).
This mentality of doing 20% by default for something you already paid is what got us in this situation.
People should be paid a living wage by default.
Once someone can tell me what, specifically, a living wage is, I imagine this will stop being the most annoying phrase on the planet.
Do you tip your local cashier in the groceries store? Do you tip the bus driver who took you to work? Do you tip a bank clerk who processed your application? If no, then this is a living wage.
Also not having "tips" prevents freeloaders from not paying taxes, which every other worker in the country pays fairly.
There can be a lot of definition but I propose " a wage where you do not need to annoy your customer for tip".
You understand that you are PAYING EXTRA for the especially poor service?