alt Hacker NewsIt would seem a reasonable case to make that their vendor should be able to assist them in these data requests, too, particularly if the vendor were profiting from the data. My own opinion is that vendors who collect data from governments like this should be subject to foia themselves.
Again I can speak only for Illinois (and 'chaps is more authoritative than I am) but for the most part you're not going to be axiomatically deriving what you can do with FOIA; most permutations of what can be done have already been attempted, and there's really rich case law. It's super easy to FOIA things! Lots of relatively normie people use FOIA. So FOIA lawyers have seen some shit.
Generally I'd predict that it's unlikely that you'll be able to do anything with a FOIA law to compel a vendor to do anything directly.