I think the problem is that we have extensive precedent in the USA that warrants to search cloud data are properly presented to the cloud hosting provider, NOT the "owner" of the data -- in fact, the data owner is often prohibited from even knowing that the process is taking place.

Others have pointed out that this is a clear way in which cloud storage is fundamentally different from local storage, which one might not expect -- being able to be secure in one's papers, a fundamental right in the US, only pertains if the papers are physically located on your person or property.

I'm overextending here, but I think the physical analogy applies as well -- if the police want to search a rented storage locker, the search warrant is served to the storage company, not the lessee of the locker.