Here's a fundamental challenge for you: can you show how this technology would lead to increase in sales? Let me give you one way in which it might lead to a decrease in sales, and it is up to you to give a convincing argument for why I am wrong, and for how there are other ways in which it will increase sales, thus making the investment a no-brainer.
People who walked into a restaurant are looking to eat. It's as simple as that. They look at a printed menu with fairly limited information, decide that an entree sounds good based on the printed ingredients and description, and order it. See, psychologically, they are already predisposed to ordering something, and they need to have a very small push over the edge to order something.
Now, consider what happens when you start showing a lot more information to a potential patron. Will this information make them even more likely to order, considering that they were likely to order already? Probably not. However, there's the potential that it might make them less likely to order - for example, they find out that the dish has a lot more butter than they think is healthy. Or that the meat comes from a farm whose name came up on the news recently as being a place that mistreats its cows. Or they decide that a dish, though it sounds good, doesn't look good in a photo.
And the counterarguments that you give to this would be "well, it's a good thing that customers eat less butter, or they don't patronize restaurants that patronize places that mistreat cows, and those restaurants should really invest in good food photographers". And these things might improve the world in general if everyone did them, but they aren't going to improve the restaurants' bottom line. The "people like paper menus" is just an excuse. The real answer is "You are someone who's a technologist first, and a businessman second (or third, or last), and you really don't understand our business model"
You are definitely not that far ahead of the technology curve. You are just behind on the "selling to a business that cares about making more money" curve.
Edit: more paragraphs.
Edit: removed a "not" that changed meaning
