Earlier quoted context omitted.
the sim is no piece of plastic. SIM cards are computers! they have a CPU. they have memory, a file system. they run applets, yes Java applets. sims are one of the most secure pieces of technology out there, part of the Secure Element standard. the sim is responsible for a lot of your phones security. lots of encryption keys live on the sim and nothing can access them at all. I am much much happier to trust the hardwa…
On a dumb phone yes contacts are stored on your SIM maybe using some kind of weak crypto, yes. On an iPhone X, it’s completely unused for crypto or security, or for any other purpose other than carrier authentication.
sims are used for more than just phones. the chip on your credit card is a Secure Element. the chip in your passport is too. these are some of the most physically and technically secure pieces of hardware ever made