The biggest problem would be designing a customer operated touch screen so easy to use a cave man could do it as in some areas like Detroit a cave man would have superior intellect.They've had one for almost a decade. I know the guys who developed it.
They tested it in a few restaurants, and it seemed to work well. But for some reason, management decided not to use it. Of course, they could always change their minds if the human order takers become more trouble then they're worth.
Another interesting system they developed but decided not to deploy was a centralized call center to take orders from the restaurants drive-thru. The call center for the prototype was in (IIRC) Wyoming, where they could find quality employees who spoke understandable English. This would greatly reduce the need for order takers, since the they would only have to staff for the actual load, rather than having an order taker at each restaurant, sitting idle for a good part of the day.
One additional point: I knew many people in McDonald's corporate, and many of them started out flipping burgers at a restaurant and worked their way up to senior management positions. In fact, former CEO Charlie Bell never worked anyplace else, starting at 15 as a floor mopper and working his way up the ladder to CEO.
I worked for what was at one time the world’s largest commercial printer as Corporate Director of Engineering and at the local plant where I was based we did our best to improve quality and safety and yes bottom line with automation while honestly doing our best to not gut the work force.
However, when the major customer at that local plant wanted a new 10 year no strike clause (we had 7 unions) and we offered in return to give them whatever other unions in the industry had negotiated, one union refused and the customer walked.
All the automation in the would could not save us from communist union scum. Corporate Bankruptcy followed by a sale of the remaining plants and that local plant is now a bunch of small businesses with NO UNIONs.
When workers use mafia tactics to blackmail a business, fire them all and let them eat their commie union dues.