They _can_ rummage through your photos. They are encrypted in transit and on the server but with a key that they have access to.
If it's not explicitly listed in the end-to-end encryption section then assume Apple can access it.
If it's not explicitly listed in the end-to-end encryption section then assume Apple can access it.
So messages are opaque but photos are not?
Notice the absence of photos from the list that follows?
> So messages are opaque but photos are not?
Yes. Unless you use iCloud backup, in which case your key is included in the backup and technically even your messages could be accessed.