There may be several different factors at play here. First of all the USA is unique in being an economic superpower and largely insulated from outside influence. Whereas Germany (another large economy) is surrounded by other nations and hence other languages, the USA is isolated between two oceans. Its immediate neighbors are of little influence as Canada speaks mostly English and Mexico is merely for vacations so the hotel & restaurant staff all speak English too.

Secondly, US English is a RISC version of British English. It’s evolved as a stripped-down version in order to facilitate rapid communication between people who arrive speaking quite different languages. But this means that in consequence all other languages are far more complex. Whereas US English has essentially only 3 tenses (simple past, simple present, simple future) other languages have 12 or more plus subjunctives. Whereas US English has essentially only 2 verbs (“I don’t do gluten, I got this great donut for you”) other languages have a multiplicity. So the effort required for a US English speaker to acquire a second language is far greater than the effort required by a German to acquire French, for example.

Lastly, English still is the language of commerce and science as well as being the default in many other domains. All commercial pilots communicate in English, most multi-nationals default to English as the common parlance, and countries with many regional languages often have English as the lingua franca — India being the most obvious example of this condition.

Fortunately for US citizens, it may not matter all that much in terms of everyday life. A US citizen posted to a foreign country by their employer will almost certainly spend their entire time speaking English. While personally I really appreciate and enjoy the ability to be multi-lingual (in my case, French and Russian, with pretty poor Dutch, German, and Italian) I also recognize that it’s a personal preference based on all manner of circumstances (I’m European, I’ve lived all over the world, I find that learning the native language provides huge insights into other cultures as well as being very congenial during social situations).

So don’t be too hard on US citizens — they have a unique set of circumstances, most of which militate against language acquisition.