> Now, the default assumption is you can call for help--which isn't always the case.
Exactly. I had an emergency situation where I needed to be taken to the hospital over a decade ago. I had a satellite phone on me, yet it was still difficult to get help due to a combination of satellite coverage (Iridium phones would have periods of no coverage due to satellite orbits) and just having a number to call (great thing about 911 is that it works from almost any phone in the US, except satellite phones).
In a similar vein, if you were in the wilderness you were on your own. If you were in a group, you could send someone for help. If you were on your own you self-rescued or hoped someone found you. Now, the default assumption is you can call for help--which isn't always the case. More likely with a personal locator beacon but even that isn't a guarantee in canyons or in bad weather.
I was on a sea kayaking trip in Alaska in the early 90s. The guide had a VHF radio but, basically, had anything happened you'd have been waiting for the bush plane to return in a week.