> Why can't we encrypt calls and texts in a way which doesn't let all this stuff get read? Like (handwaving) either trust the network and encrypt with a key they provide, or else some form end-to-end encryption (where maybe generating keys is part of what happens when you activate a sim card or something)?

We can have E2E encryption on cellphones today, just make calls and send texts over Signal (with other people who also have Signal installed).

Here's an article on using SIM cards as a secure element: https://nelenkov.blogspot.com/2013/09/using-sim-card-as-secu...

I would really like a hardware interface for changing a key, or a mechanism where you flip the card over to expose a separate set of contact plates which have write permissions. Stock Android will allow carriers to fuck with your SIM card sans user permissions.