Sure, but they still need to get an app somewhere. And also all the people they want to communicate with need that app. And that are not just other politicians,

Sure, but they still need to get an app somewhere. And also all the people they want to communicate with need that app. And that are not just other politicians, with them they can anyway communicate face to face in meetings. But politicians can't meet up with shady people. If they meet up with CEOs it's always on some record. But with Signal they can just text with them in secret. Signal is there. And you can also install it on private devices, that's what politicians like even more. That even their own intelligence agency can't read the messages. A lot of politicians are corrupt, and they don't like laws that make it harder for them.