Well, you are right. But the message as well as the medium can be privacy-respecting. Even with encrypted messages, a lot can be extracted from metadata that is a part of the medium.
These days pager tech has advanced to support public-private key encryption for messages. So the messages being in plain text is less of a concern.
These days pager tech has advanced to support public-private key encryption for messages. So the messages being in plain text is less of a concern.