>SIM cards have their own cpu, memory, and OS running on them

That might be the case, but they still rely on the phone to feed it information. I doubt the sim card interface provides a way to send the currently connected wifi network or what apps are installed.

No but they can correlate things to a ridiculous amount of resolution. Sure, millions of people hit the Reddit API every day but I can guarantee no other person on earth hits it at exactly the same time as you do, repeatedly.