A strong, domestic TLA should be assumed to hack or intercept all of them if companies are local. Then game changes to the caller hiding their identity. Text-to-speech and burner phones can do that. However, messaging and email over WiFi's on devices bought with cash hides voice, has better clarity, allows file transfers, and can still do voice as an attachment.
Good for people I told to keep their burners off unless transmitting from semi-anonymous locations. That's their best privacy technique if they're non-technical.
And how well did they follow this advice? Would you know if they didn't turn their burner off, or even bother with a burner? "They didn't die in a prison camp, so they must have done things right"? Lay people who value privacy can fuck up their opsec pretty bad without noticing consequences. This is getting in to tiger repelling rocks territory, where it's no measure of one's stealth skills by hiding when nobody's looking.
It boils down to two areas of trust: a computer that's potentially malicious against a nation-state with stuff like QUANTUM; their ability to go somewhere remote/crowded and make calls. Im thinking lay people can do the latter because they have for ages. The latter also takes HUMINT to counter which is a precious resource they can't throw at all the reporters simultaneously like electronic attacks.