Re: Prior art?
McDonalds is 100% prior art.
A key pre-Mac feature of each small USA town was the local burger joint somewhere downtown which served its own unique burger, had its own regular customers, etc. These were all a bit scruffy, food was hit and miss, though some of them served fairly decent food. I caught the tail and disappearance of the last of them in the 1980-es during my first visit to the USA. The local burger joint in the uni town I stayed served double the size, double the quality for half the price of what McDonalds was serving. You had to endure the piercing inquisitive "who is this guy" looks by the local population though as well as answer questions from the other punters.
McDonalds replaced these with a clinical industry oriented specifically towards the traveling salesman. All of its recipes are prior art from local burger shops (it does not hold specific IPR or trade secrets on dishes the way KFC or Burger King do).
Early on the traveling salesmen were the guys which fed the growth of the Mac. They knew that they can eat something that sucks, but sucks to a known level and not be growled at by local hillbilly troglodytes anywhere they go. Nobody was asking them questions about the local football team either.
Then, the locals followed them and the rest as they say is history. The burger joints are no more and Big Mac took over USA and then the world (only to be displaced by other chains nowdays).