It seems hard to have empirical data here, but even just the parallelization of it seems to bias in favor of mobile ordering.

Part of the reason I hold this particular opinion weirdly strongly is because of the confusion I feel when I'm sitting in line in the drive-thru behind a van where a family or a group of friends is trying to crowdsource food for 2-4 people live at the window, or rattling off a complex coffee order and hoping the audio quality carries it through.

If you're ordering something different every time, and not anything complicated, and it's just you ordering, and the tech in between you and the person listening is decent, I'd bet that you're right and just telling someone your order is less effort. But as soon as there's any stray variable, mobile ordering handles the complexity much more smoothly.