while i agree that this "doorman fallacy" happens, and i also agree that it can happen in the context of restaurant servers, i completely disagree that this is an example of it.

problems cited: people ordering at the same time (limited by presence of a single QR code). splitting the bill, knowing what was items were already paid for or who already paid for it (made difficult by interface).

these are examples of problems where the tech solution can easily be much better than the human solution.

for example, you'd just need a larger number of QR codes. or, i'm under the impression that nowadays some phones can read QR codes even at weird angles; in this way even a single QR code could be read by multiple people in parallel. meanwhile notice that human servers can only take one order at a time.

and obviously super simple modifications to the interface solve your problems with the bill. but it's more often than not an ordeal to arrange with other people and the server to pay for 1/4 of the fries and 1/2 of the salad or something like that (unless the server themselves has access to a tech solution).

ways that the server could be better than the tech solution would be, for example, explaining dishes (ingredients, size, taste) or making suggestions.