Phones have displaced paper money and credit cards as the preferred way to pay for a bill at the end of a meal.
In Europe maybe? I've never seen anyone pay with their phone. Not in big cities and not in rural areas in the US. I will never do financial transactions with my government spy device. To each their own obviously.
As for when I am ready to pay, I go to the counter and give them cash or I might use a debit card if I am picking up everyone's tab. If they give me grief then I simply do not return to that establishment and they will get negative reviews.