I think you are assuming that after the nuclear war, survivors continue to live in fallout shelters and need to focus all their energies on personal survival for years and years whereas I believe that society and technological civilization reconstitute itself over months.

At least as long as a prepper can survive alone in a bunker on rations.

It'll be a bit like that "WWII is still going" delusion that held out deep in the jungle on isolated islands.