Guy, I understand your concern. I'm less concerned about breakdowns than I am about a medical emergency. A medical emergency could be a vehicle accident, a heart attack or stroke, a bee sting or any number of potentially life threatening incidents. In emergency medicine there is something called the golden hour. Basically, if you can get someone with serious traumatic injuries or a serious medical condition to an acute care facility within one hour, it greatly increases their chances of survival.
One of my sons is an avid backpacker. As a young man (19 or 20 years old) his first significant backpacking trip was a 10 day trans Sierra solo trip. We insisted he let us buy a Spot GPS tracker. It enables you to program it for intermittent tracking (you have to program the interval in advance) and it enables you to program three custom messages. It also has a 911 type emergency signal and a helping hands signal for non-emergency assistance from family and friends who you select to be notified.
My son goes on 4 to 6 week backpacking trips every summer. He usually spends a week or two with my other son or a friend but the rest is a solo trip. So for us the Spot has been very comforting although he doesn't usually enable the tracking feature, he will always send an I'm OK message when he sets up camp at night. He also gives us a very detailed itinerary and map of his planned trip.
On one week long trip with four friends of his and my younger son he had the tracking enabled. Since some of the the others were inexperienced backpackers, we had made contingency plans in case of an incident or emergency. It was all high elevation, 9000 to 13,000 feet so we made a plan that if someone got altitude sickness they would exit on the western side of the Sierra rather than try to climb back over the pass to get back to their vehicles on the eastern slope near Bishop. We were monitoring his GPS tracks and it appeared to us that they were headed towards the western contingency exit. It turns out that they were in a narrow canyon and lost service for several hours. When we finally got another GPS track it was obvious that something was wrong and that they were headed for the western exit. I ran home from work, threw a few essentials in my truck and hit the road on a seven hour drive to get to where we agreed they would exit in an emergency. After about four hours of driving not knowing what was going on I got a call from my son on a satellite phone at the Muir Trail Ranch, which is a remote resupply ranch for hikers on the John Muir and the Pacific Crest Trails. It turns out that the novice backpacker got lost and his experienced friend developed altitude sickness and couldn't make it back over the pass so they headed west to exit.
We met up at Florence Lake at midnight. I happened to have oxygen so I put his friend on oxygen and drove out while my sons decided to go back the next day and try to locate his lost friends. I told his friend with altitude sickness that I could take him to the ER but he wanted to get back to Sacramento to his wife. We arrive at about 4 a.m. and he ended up going to the ER and was diagnosed with high altitude pulmonary edema. He spent two days in the hospital on diuretics to get the fluid off his lungs.
The lost hikers made it out the next day. Sorry for such a long story but if they had the ability to send a text message things would have gone much smoother. So having the ability to communicate via ham radio or satellite can be extremely valuable and can potentially save a life in certain circumstance.