Like say, old time Quake/CS servers, those info are pretty much not going to be transparent until it's setup and run by a non-profit org. Because, the best they can do is to provide monthly server bills and if they setup account that are dedicated to pay for that bill. Cause otherwise too much personal info is involved, and server owner does not owe you that as well. You either trust the owner from their past performance, or join one that matches your standard. embeded content(img or video use other service) does not consume storage nor bandwidth to the server owners. (PS. malicious owner can always fake reports etc and you will have no way to verify. )

However, I do not know the sharing part works and how that's been handled. Say, lemmy.world have more user and needs to update to other instances more if people subscribe from different instance? I don't know the percentage of incoming traffic compare to out-going and what tier of bandwidth we are talking about renting server wise.