I love ny phone. It's my library, my calendar, my prosthetic memory. But IF my phone cooperates and scans the QR code correctly or at all, IF my fat fingers cooperate in poking the right places on the screen, IF my senior eyeballs can read the font size or IF increasing the font size doesn't make the text break awkwardly, IF the menu choices fit on the screen without scrolling too much (see above fat fingers)(and I like doing a fast scan of the entire menu to see categories), and on trains, IF the surface on which I am sitting/standing doesn't lurch suddenly (like trains never do that) and I poke at something that makes the page vanish, ... That's all without adding in the killer if, mentioned by others, functional internet. I've had an internet connection on trains that told me yes, I'm connected to the train's internet but no, I'm not getting anything useful from the outside world.
It would be cool to use an internet available menu for planning (is there anything they're offering worth staggering to the cafe car to get, or that my stomach will tolerate today). It would be very cool if staff could update said menu on the fly (oops, they just ran out of cheesecake). But sometimes the old-fashioned way is still the most functional. After all, we still use the wheel.