Outside of cheap takeout places, I neither need nor want to see pictures of food on menus, because I can read the menu and decide for myself whether I want to try something based off the description. I'd rather a blown out flash photo of a plate of noodles than a generated image though.
I was under the impression that FTC laws require food advertisement photos to be the "real" thing. I don't know if the FTC covers food service but if so I wonder if they just don't want to bother slapping restaurants with fines over generated product images in menus (or if menus just aren't covered by the same regulation). Also I wonder if there's some grey area when it pertains to "photos" vs "generated images" (though the latter is clearly intended to stand in for the former).