@sean if you are talking specifically about burgers and fries of the "quality" served up in typical fast food places, automation has been a list effective option for over 20 years, but the ability of it to replace workers has been somewhat underestimated. Automated cleaning and other maintenance is a LONG way off.
COMPLETE automation reduces fast food outlets to vending machines. I have seen such machines that cook and assemble burgers and fries. They are high maintenance and QA is an issue.