I travel a lot for work. As such, I eat out a lot. As such such, I look at a lot of places’ menus without physically being there (since I don’t know the area, I don’t know where to eat, so I look at the reviews and images posted online).
A restaurant’s soup selection will likely not be the thing that decides if I eat there or somewhere else, but sometimes soup is the only side dish that sounds appetizing, and if I don’t know what kind of soup the restaurant serves I’ll probably just pick somewhere else.
In theory, sure,
In reality, I promise you no overworked restaurant staff wants to bother with updating a website daily on the off-chance someone needs to know the soupe du jour. You’d probably just get the wrong information because no one updated it.
If you absolutely must know the soup availability, you can always just call the restaurant. The employees will make fun of you behind your back, but they’ll pretend to be glad to inform you!
And most of them are fucking PDF anyway, so another layer of editing and likely a layer removed from daily management