[Jtsummers]

The USPS is restricted by the Constitution and other legislation on what it can do.

From: https://www.uspis.gov/wp-content/uploads/2019/05/USPIS-FAQs....

> 4. Can Postal Inspectors open mail if they feel it may contain something illegal? First-Class letters and parcels are protected against search and seizure under the Fourth Amendment to the Constitution, and, as such, cannot be opened without a search warrant. If there is probable cause to believe the contents of a First-Class letter or parcel violate federal law, Postal Inspectors can obtain a search warrant to open the mail piece. Other classes of mail do not contain private correspondence and therefore may be opened without a warrant.

Companies hosting your data aren't similarly restricted (though if the US government wants access then they'd be restricted by the Constitution and legislation again). A company's ability to look at whatever you give them is only restricted by your contract with them and the technical limitations created by how you share it (upload encrypted files where they don't have the key? they can't really do much). They may have some legal restrictions on some kinds of data, but it's not going to be uniform across the globe so you'll have to take care with which companies you choose to host your unencrypted data.