I pay cash always at restaurants. If an establishment is going to try to refuse my cash or charge me some fee afterward, they better have signs prominently posted or tell me up front before it’s time to settle up because I don’t carry credit cards or a cell phone. Cash for my tip is handed to the waitress.
The vast majority of my restaurant meals are business travel and I’m required to use a corporate card. Right now, it’s 30-40 meals a month