Everything should be encrypted, always. We live in a time where hardware for en/decrypting is so fast and cheap that they can be included in any device. If you send somethig through a it should be encrypted. If you send something over the air, it has even more reason to be encrypted. I see no scenario where it should not be.

HOWEVER! For law enforcement and other official governmental agencies I think all communication should have to be recorded. And failure to do so should have very high penalties. Transparency should happen after, not during the communication.