I don't think you understand what "3rd party" means.
The storage unit is a 2nd party. You (the first party) have a contract with the storage unit (the second party) to store your things. There is no third party.
Compare that to the phone company, where you (the first party) talk with someone else (the second party) using the phone company (the third party) equipment.
Thanks, I didn't realize I made that mistake. Maybe a better analogy would be a broker who is facilitating the transfer of some property, and the cops unreasonably searching/seizing the property while it's in the broker's possession?
Here's the most apt analogy regarding "transfer of some property": The police aren't allowed to search a package without a warrant, but the USPS does photograph all U.S. mail (160 billion pieces), and sometimes provides that information to a police investigation.
After all, what's on the outside (the metadata) is public.
But in general, the owner of your apartment complex cannot give police permission to search your apartment, and the owner of a storage facility cannot give permission to search your items.
The storage unit is a 2nd party. You (the first party) have a contract with the storage unit (the second party) to store your things. There is no third party.
Compare that to the phone company, where you (the first party) talk with someone else (the second party) using the phone company (the third party) equipment.