Okay now I'm stretching the OPs idea a little bit, but America is big.

How people live in South America never needing to learn other language than Spanish and plausibly never interacting with a foreign language outside movies. I spent some time in Chile, the place I lived in had a nice janitor. He did not speak English, I only knew a few loose words in Spanish so communication was... peculiar. Only after 2 months of awkward interactions he realised, that I probably am not Spanish native speaker and it hit me.

When your entire life in a continent where everyone speaks flavours of Spanish or Portugese, you can have successful, international career only in Spanish, participate in all kinds of rich culture only in Spanish and all signs and labels are only in Spanish, huge majority of tourists speak Spanish... it is not immediately obvious, that people may not speak Spanish.

Don't get me wrong, it's not dunking on "dumb spanish speakers". There are ton of places in Europe where people disregard English, where it's famously hard to communicate in anything other than the local language, but the fact, that other languages exist is apparent to everyone once they learn to read. Awareness that people actually speak these languages is the most natural knowledge from ground school as we learn that "Germany speaks German. Italy speaks Italian" etc. A perspective which does not involve being in constant proximity to numerous foreign languages felt like something that made no sense to me in the past until I actually came into contact with it.