Re: So all phones are tracked
They have a unique serial number, so Apple can tell when it is checking with Apple's servers to check if there's a software update, or install an app, etc. If the phone is on the "sent to be recycled" list and appears again, they will know. They don't have to even know its location just that its "still active".
That's not the same in any way shape or form as Google tracking what search terms you use, who you send emails to, what ads you click on, what URLs you visit in Chrome, what apps you use and for how long on Android etc. etc. Apple is just tracking whether a device still exists or not.