It's likely most of us Americans don't know about this fun fact.

I've certainly not seen anyone frothing at the mouth about it in the francosphere. It's a non-subject, we just updated our textbooks and moved on. Whereas in English-speaking media even reasonable actors mentioning Pluto in passing will pointedly remark on its status one way or another. Americans won't admit it but the only reason that's a thing is chauvinism.

It's funny how being bilingual one spots a lot of small semantic or cultural differences that amount to large paradigm shifts between languages. Like how most French people were taught the hydrocution myth (swimming after a meal supposedly being deadly), older Koreans believe fans to be dangerous to use while sleeping, and English speakers associate vanilla flavour with blandness because of the (English-specific) synonym even though the flavor itself is very powerful and no less overused than e.g. strawberry flavoring.

What's less funny is how when you point out such a difference some people get Big Mad about it because they can't admit that some core belief from their childhood is actually a specific sociolinguistic quirk not shared by the rest of the world. People get tribal about the weirdest, most inconsequential shit.