RMNP changed this a bit after a week long (or so) search for a solo missing backcountry ranger who eventually was found deceased from a fall - they now have GPS trackers transmitting their location when they transmit on their radios and they file travel plans and have regular checkin with dispatch so response to their being overdue can be prompt and effective.

They may still be alone but they have a guardian angel on close watch for them.

We might be able to do the same thing with PLBs and ham radio or cellphones (or satphones).