That is actually not something very unique. This happens in quite a few coutnries, and in that case the photographer will simply have to get the permission to enter and take the photo. Sometimes simpler than other times of course :)
The same of course goes for interiors of monuments, which are in some cases separately protected.
This is no reason to remove them from the lists though - they are still monuments. And when it is the only thing left to photograph, the owner is more likely to be swayed to give permission once.