You answered your own question. Yes, it _is_ that messages are private vs public. Telco has no concept of public. Everything is direct communication. Similarly, you can talk to as many people as you want on twitter in DMs about doing illegal things, and if none of them report you, you won't be cancelled. (I cant confirm whether or not this will trigger a law enforcement investigation or not though). This is why so many spammers user forms of Direct communication. Because the spam ads/posts/etc are usually moderated into oblivion.