I was under the impression that the hamburgers were already machine made, and the patties delivered ready-to-cook, to the franchise fast food joints. No? That's what it looks like, from te customer's side of the counter.
So why not a machine that does all of the steps in the same place?
The actual cooking of the burger shouldn't be all that hard to do automatically. Fast food places already use automatic machines for things like grilled cheese sandwiches.