The cost to take a menu and print it for each table plus some is non-zero. The cost to replace the old online menu with the new menu online is near-zero, besides man hours for the manager/chef to determine the seasonal cuisine.
Source? All i've seen has been CMSes/SaaS platform which definetely shouldn't require a dev to update.
I've walked out of few places because they failed to present a proper hard menu. Seen few people struggling with their phones.
Totally ok with funny thing until there is a choice. Who prefers it - good luck struggling with your phone. I am not one of you.
The restaurant could also lose customers who are tourists, who don't necessarily have a data plan while traveling. While it's a bit more convenient for the restaurant, the convenience comes at the cost of the customer.
Also, the UX for many of the menus is often pretty bad (with diners often asking: "how do I place an order?" "did I place an order or not?" "how do I go back?").