Ideas
"Previously if you put a Food Van there, you didn't need to hire it. It was operated 24/7 by a succession of Sims. " I am having the exact same problem with community spaces and the food vendors. Normally I turn community places into maker spaces then create a club to use it. Before recent updates (I thin it was was after Lovestruck or the update that followed it) vendors would automatically populate the food stalls now they don't turn up at all and I cannot even click on them to "Hire Vendor". I recently repaired my game and started a completely new save converted two of the community lots to maker spaces as they already come with a food stand but it was still the same result. I never play with mods and don't have any CC either I have added things to the community lots and saved the lot so it can instantly be placed as a clubhouse but that is it. I've had to put a fridge and counters in each space so my sims can eat while on the lot.
Hi
Definitely things have changed since an update.
I suspect the issue is that now non controlled Sims ONLY autonomously use items that are required items for that venue type. Or ones listed at the bottom as items to choose from eg Recreation Items in a "Recreation Centre" venue, or Park Items in the "Park" type.
If the item you want them to use is not listed there and you modify the build to include it, your Sims can use it but no one else will.
From what I can see, changing the lot type seems to indicate that Vendor stalls are only listed in Marketplaces and Parks.
However, Community Spaces are totally busted. They are the only venues where they now autonomously use Fabricators when and only when it is a Maker Space. However, when it is voted in as a Marketplace it has Vendor vans in their list but they can't be hired or autonomusly staffed (like they used to be). There are sales tables there but they can's be "owned" and no one else uses them. So they are busted.
If you want Vendor vans, from what I can see your only option is to make your Club venue into a Park.
I changed the Hare Library to a Park by putting in the required items including a Vendor van. It can now be hired for 100 Simoleons and someone turns up. Now they won';t read the books because they're not listed item for that type of Lot. But they do use the computers and chess tables because they are. Parks that the program makes like Desert Bloom has a bookcase and Sims autonomously read books there, so go figure.
To confirm that Vendor vans work in Parks, I added a Vendor Van to Desert Bloom park and had to pay 100 Simoleons for someone to turn up. Mind you, it's possibly good that you can control that because I once had the Sim manning it die from Heatstroke.
Hence they are the only venues where they will be operated. You could check on that yourself by changing the Club venue hang out to a Park.
A work around is to put in a kitchen.
Depending on lot type as chosen in the build mode, if grills are listed in those "Venue" items, they will automatically use those. (If there is a refrigerator nearby, if you use the Put Away command on food cooked by someone else, they will put the plate in the refrigerator. Some non controlled Sims will take prepared food from the refrigerator, but possibly only Gluttons? All seem to take drinks eg milk, from there.)
They have a list of "Community" items for each of these venue types, containing music speakers, bins and toilets etc but Vendor stalls are not included in this list of Community Items nor are Dumpster bins.
So the easiest "fix" would be to include Vendor Stalls (even a basic one) in "Community Items" then you add it to the venues you want to use.
They have all sorts of bins, but I'd like them to put a Dumpster bin in as Community Items too.
Fabricators and Guntdach Recyclers could also be listed in Recreation Items.