I honestly prefer self-checkout. I may not be as fast as the cashier, but I am reasonably fast and I don't have to talk to anyone.
I'd probably feel the same about fast food orders. I don't think the same self-checkout system would work, but I'd probably use my phone if it was easy and I didn't need a special app. Just let me scan a code and enter my order from a parking lot space. That way I still don't need to talk to anyone, no issues with crappy mics or AI, etc. I'm guessing everyone would be happier (workers don't need to intuit crackly mics, I can check if it comes with pickles, etc).