Well, before the 19th century there was little actual knowledge of what was life like in the Bronze Age, as there were no documents of it. Same with Fallout, all the papers have gone and been destroyed, and computers never were apparently so popular, so you lost your only reliable source on pre-war life. Especially when 9 out of 10 people died in the war, and the rest soon after before the next generations started rebuilding humanity.
Washington knows quite a lot actually. I assume he used to be a scavenger himself, and later retired with his loot collection from all around D.C. Historical investigation can reveal anything with evidence and imagination.
Well, that's why I put in the clarifier of "several open vaults nearby." It's one thing if all the knowledge was stored on books that got burned up; it's quite another if they're stored onto a Vault's Computer System that seems to never need replacing or repairing... All you have to do is go to a Vault and BOOM! Access granted!
Dude, there's people in the real life US today who grew up there, went through school and have access to both the internet and public libraries - and still don't know or get things wrong about US history.
Mr Washington's mistakes about the american history is not that unusual or strange given that 200 years have passed and many records were lost.
You'd be surprised how many actual historians in our world that gets things wrong about things that happened 200 years ago. And not only because of conflicting records.
Well, the thing is Mr. Washington is considered the expert in US history (minus the PC, Dad, and the guys from 101, Enclave, and possibly the BoS.) And it's one thing to think that it needs to be ratified by the King, it's quite another thing to think that planes existed in the 1700's.
Also...
258: Visit Old Olney at your own risk!