All of which could be accomplished with ease, along the side of the road if need be, using very basic tools, and without the need for any scanners or computers.
And I respectfully disagree. No mix of SAE and metric fasteners, for example. Also, simpler and easier to fake parts. Heck, you could keep driving with one of three fan belts still functional as only the water pump was really necessary.
One example that comes to mind is when a carb took a complete dump on a 10-mile long trail. It took a few tries, but we found the perfect size "metering rock" to stick into the fuel hose and make the fuel flow into the engine right to keep it at the desired rpm.
Later we discussed how tall of a mast would be needed to create enough pressure to keep EFI working. Not as simple as putting a can on the cowl if a normal fuel pump went out. As I recall, it would be some 60 feet tall - not practical on a rock trail in the pines.
I could keep adding to the list, but I'm sure you get the gist of it.