Sure. Fax only makes one printed copy. It isn't stored on a server where anyone with admin rights can also read it; it isn't kept on backup tapes when the mail server is backed up - and those tapes could be held for years, or sold/disposed of without being adequately erased; the fax machine usually cannot be accessed remotely by using a phone app, or a program from an employee's home. Email accounts can be hacked, or passwords guessed.
If you want to hack a fax machine, you basically have to stand in front of the fax machine to do that.
