Notice that when someone grabs their phone, they're not just grabbing a web browser but also their personal entertainer. Besides chats, many people also have various apps trying to nudge them into engaging with it. I have never been in a restaurant without menu though, I just imagine that I'd end up on HN while contemplating what to pick out of sheer habit and muscle memory

Besides that, there are people who have no smartphone or an empty battery, can't use a smartphone (one of my grandparents can read a menu with a pocket magnifier, but a touchscreen phone is too cumbersome and so they don't know how to use that; another grandparent has memory issues and never learned how to use a smartphone), don't have signal (you need to provide WiFi), have an allergy and need to ask questions or ensure that some ingredient is really taken out, etc. I'm not against the option to order impersonally but a good kitchen communication system would go a lot deeper than slapping wetware with slopware