Or perhaps that nobody had the common sense to call a tow truck, so that they can get down the mountain without relying on a field repair to a safety-critical system.
This makes a lot of assumptions about how far into the wilderness they were, time of day, accessibility of the roads, cell phone signal, and so on. To just hand wave and call it "common sense" is silly without the rest of the context.
And for me, 100 times out of 100 I'm taking the capable guy who can fix the brakes on a trip like this over someone who's first and (likely) only instinct is to call a tow truck.
This is true. I spent a week hiking the mountains, where I often could see exactly the same environment that has existed for millions of years. But at all those times, a hut serving beer and warm soup was always an hour's walk away.
Not invented here is the tendency to avoid using or buying products, research, standards, or knowledge from external origins. It is usually adopted by social, corporate, or institutional cultures. Research illustrates a strong bias against ideas from the outside.
Sounds like they were already down the mountain. Stopping to call a tow truck while traveling down the mountain would involve having working brakes, which the scenario suggested wasn't the case.
And for me, 100 times out of 100 I'm taking the capable guy who can fix the brakes on a trip like this over someone who's first and (likely) only instinct is to call a tow truck.