Can speak on this from two very different POV's:
As someone who runs a group, I totally get how convenient the soups are. Carrying less weight while getting SO MUCH hunger & hydration from a soup is massive (and they're cheap compared to what you'd pay to get the equivalent amount of food and drink elsewhere). When we as a group got soup and other alternatives, the other alternatives are never touched really unless it's a last resort.
As someone who owns a restaurant that CAN'T provide soups, it's absolutely brutal trying to get contracts with groups / businesses as they all just say "We get soups but cheers" or something along those lines and because of what I said above, I totally get it.
From an RP perspective, I feel like people wouldn't have a very good diet if they live on soup all of the time, so you'd want to give people a reason to branch out to other things but it comes back to the fact soup is just too convenient to pass up on. Fairly cheap, lots of nutrition, and 1 pocket space, there's almost no reason to go for any other food unless you just don't have soup handy at that time.
I think a fair solution would be to provide the restaurants that can't make soup some kind of alternative that can compete.