A lot is made of this (usually by Europeans), and tends to portray Americans as stupid, lazy and arrogant (not saying this is true of your post). In reality, it has a lot to do with the fact that the US only borders one country that speaks a different language (two if you count Quebec). Few Americans (as a percentage) ever travel outside the country, because it’s too expensive, too far, and fairly difficult to get a passport. A lot of people here know basic Spanish, especially if they work in hospitality, construction, or farming. But if you learn French in high school (as I did), you get zero chance to ever use it in a practical setting, apart from a trip to France once a decade. I’ve never done business with anyone in France. In terms of effort and reward, learning French was a poor use of my time (and I spent 6 years on it). That knowledge has mostly atrophied away now. In the meantime, I’ve picked up an almost equivalent knowledge of Spanish without any effort at all, because Spanish speakers are a large percentage of the population where I live.
Compare this to say, Germany, where you can cross one border (quickly, easily and cheaply) and encounter Danish, Polish, Czech, Italian, French, Flemish and Dutch. A couple hours more on the train and you hit another 10+ languages. With open borders, you are very likely to encounter people who speak other languages, and likely to do business with them too. It shouldn’t be surprising that Europeans speak more languages. It’s emphasized in school because it’s useful when you get older. More proof is how few people in England learn another language. Most people know a bit of French (look, you can get there easily and cheaply), but that’s about it.
It also helps (or hurts) that so many people around the world speak English. It gives you little incentive to try to learn their language- I can bust my ass for 6 months trying to get a basic working knowledge of Icelandic, but when I go there and try to talk to someone who’s been learning English since the age of 5, guess which language is going to win. Now if you’re Icelandic, you really have no choice but to learn a few other languages, because your native language is only spoken by about 300,000 people.
I am trying to learn Mandarin, but I don’t see it as necessary so much as polite. I don’t expect to ever be able to carry out a detailed technical conversation in Chinese, although that would be extremely helpful. Most of the time the front office people we deal with speak English (sometimes well, sometimes not), but the people doing the actual work don’t speak English at all, so instructions have to be translated by someone who may not really understand the technical part.