Because its not. They have all the filenames and checksums/hashes, access/modification dates, and also take "temporary" custody of the key when using icloud.com. Zero-knowledge does not have any of these things.
The problem is that any of that information is obtainable by a warrant because Apple retains possession of such data. The whole point of this exercise is to eliminate that possibillity.
The problem is that any of that information is obtainable by a warrant because Apple retains possession of such data. The whole point of this exercise is to eliminate that possibillity.