> 2.) Customer can open an app, This assumes that /every/ customer: 1) has an appropriate cell phone (i.e., ios and android apps are incompatible with each ot

> 2.) Customer can open an app, This assumes that /every/ customer: 1) has an appropriate cell phone (i.e., ios and android apps are incompatible with each other's devices) 2) is willing to install said app Both assumptions fall down when a customer arrives who: 1) has no cell phone or 2) is unwilling (due to privacy or other reasons) to install said app (I would fall into this category myself, I'm not /ever/ installing random restaurant X's app in order to make a payment) or 3) left their cell phone behind in car/office/at home, etc. The current process works no matter the technical level (user or device) of the customer.