If you think the technology is there, what explains its lack of adoption? I don’t think McDonalds et al. are in the business of leaving easy optimization on the table.

(My own guess is that touch screens are still more expensive and buggy than humans, and machine-made food still trades off novelty to be profitable. But I don’t know.)

McDonalds seems to be rolling them out slowly, but are actually cutting staff while simultaneously increasing their fleet of touchscreens. I see a lot more employees alternating between doing work in the kitchen vs. taking orders at the cashier. This is even during relatively high demand times with long customer wait lines. This is just an anecdote though, the data may disagree.

I'd also be curious to see any user interface studies on these touchscreens. In my limited experiences, they are completely slow and thus an awful experience. They clearly are trying to sell more at every step instead of being useful and efficient for the end user.

McDonald's already uses touchscreens in some locations. I'm guessing the rest comes down to tradition and the availability of cheap labor preventing the motivation to turn existing technology into a packaged franchise of automated restaurants.