First let me say, I have done no research about any of this, this isn't a research paper I made. This is me playing the game, with experience as an American, casual research into history. Learning about civilizations, and being in the military. I have come to the conclusion, the Fallout universe makes zero sense.
Why does it make no sense? Because it doesn't accurately portray what humans would do in these situations. The people simply stop, they barely adapt, they barely invent, all they do is slap together old tech and try and get it to work.
No one is fabricating/ mass producing products on a scale I believe you would see. In a situation like this you'd imagine seeing fishing villages pop up, hunting villages pop up. People would be hunting gecks, gathering hides, selling hides to a community which would then produce armor and weapons, which you as a player could then purchase at will. Want to armor 3 companions in matching gear? Good luck finding the same gear.
I believe in a real situation there would be bazaars where geck corpses are hung from string at shops dotting the streets. You really don't see that here, you see pockets of what used to be, with people trying to patch together old tech.
I can fix this gun with duct tape! But I can't make a bow and arrow? No one is making spears? I have to go and find spears around the world, you're telling me no one said. "Hey, you know what, I have all this wood and very little ammo, maybe instead of slapping together old tech I should go back to much more available pre-tech."
Armor- I know the whole, duct tape armor look is cool in Mad Max. But these people are fixing robots, no one can tear these cars lying around into scrap metal and fabricate a full set of plate armor? No one is that smart? Not even the guy fixing the Solar powered generator plant? He couldn't figure that out?
Transportation. Okay, so there's people in VTOLS. But no one takes an abandoned car, strips off the brakes and stuff and hooks some cattle up to it to make a wagon? No one can make a wagon at all? Did we lose that technology?
Furthermore study of WW2 has shown us that a military without vehicles will pursue whatever allows them to increase their movement speed. In WW2 American parachute men utilized bicycles to move around Europe faster. In a situation like this one, I can assure you the military would not walk around the wastelands like idiots. They would make wagons with animals, they would create bicycles. They would do something. Hell even Chariots would be superior, why doesn't the legion have chariots.
House Construction- Look I get it, the world has ended, but why is your house made of 500 pieces of rusted metal. There are mud huts, there are tepees, wigwams, there is wood around, and (here's an idea) you can simply get a piece of metal large enough to cover your entire wall, you could make the pieces uniforms. Or you could make a DFP (Defensive Fighting Position.) To live in, like a military bunker.
I would understand if the world was like this 10-30 years AFTER the bombs hit. But for hundreds of years? Utter nonsense.
I love Fallout, but the world/ lore doesn't accurately portray humanity.
We survive, and we thrive. This is just a bunch of people desperately living in the past.