It is rather jarring to be stuck in the woods with Google Maps offering turn-by-turn navigation back home while the emergency room only gets a vague triangulated position (which might be wrong entirely if the signal gets reflected off of something).

Of course these days such a system has been added. Bonus feature of the (at least American) feature: the system can be activated remotely, even if you're not actually calling in an emergency. The European ETSI spec is pretty funny, it basically comes down to sending an SMS to a Secret Number with a Secret Format containing your coordinates to prevent abuse (both can be found very easily); at least that supposedly only activates when you dial the emergency services.