I think this feature is required for emergency calls if your specific carrier is not available/in reach - in emergency mode after the phone is restarted, it does connect to any carrier when calling 911, not only yours?

It does indeed. When making emergency calls a phone can switch carrier though generally it will only do so when the main carrier is unavailable or overloaded.

What is it’s a mentally ill person who is about to kill themself?

That’s the majority of uses for the system in the UK. People love to run away and waste police time.

That’s not a good excuse for mass privacy violation.

“A mentally ill person called 911 and said they were going to kill themselves” is a much better justification for pulling GPS data off a phone than any of the rationales I’ve heard from US companies or the government.

What about the other 329,999,999 Americans who aren’t trying to kill themselves at that time?

It’s a cost vs benefit analysis and the cost is pretty damn high.

They’re not calling 911, so their phones wouldn’t respond with a gps location.

I’m not arguing all locations should be collected, just that “during a 911 call” is a really reasonable time to do it by default.

But the question is - does the functionality just open the door for everyone else?

If it could be adequately controlled so that it couldn’t, I would agree

And it’s typically disclosed in one way or another.

Between buying a phone and reading the OS EULA to providing an E911 address to my carrier, I can count at least three disclosures of this feature.

Nothing is secret or magic here.