I.e., it's because none of this privacy technology is built-in as the default into our communications infrastructure. Therefore, for the average person (and even for privacy-conscious techies), it is inconvenient and difficult, and you have to convince the party you're talking with to also install and configure something that is inconvenient and difficult for them.
I'm convinced that the question of why end-to-end crypto isn't the default is a political one; i.e., there is pressure not to do it.