That's exactly it. I work on a website that makes ancient artefacts accessible. A lot of them are in museums. You wouldn't believe how many museums:
- don't want to show you their archive
- don't want to let you take pictures
- want you to share only low res pictures
- want you to get permission before you can "publish" their artefacts, etc.
It's extremely common for museums to have courtyards or basements with special "unpublished" pieces that they don't let anyone see. You have to be a special friend of the director or something to get to see them.
It's ridiculous. Fortunately, the people working on the website are relentless, and manage to eventually get collection after collection photographed and added mostly by being patient. For some collections it took 20 years before they got access -- but since everyone uses their website, and everyone apart from the local museum director wants the stuff to be in there, eventually they get access to most things.
(Museums in Italy are the worst, allegedly. They really think they own antiquity.)