They tried completely robotic fast food places years ago. After a very brief novelty wore off, the public lost interest. To make matters worse, the robots maintenance and restaurant cleaning required so much labor that it was just cheaper to hire people.
The current generation of tech is much, much better. Europe has fully automated pizza vending machines that make the food from scratch.
Bring back the Automat! I loved eating there in Manhattan, NY, with my grandparents, when I was a kid living on Long Island.
Fresh pizza making bot/vending machine: http://youtu.be/j7_lxiU8eLM
Apparently they’re doing really, really well in Italy.