I'm going to echo what someone else said earlier in the thread.
The USA is exceptional in that it is separated from other countries by oceans, is geographically
massive, already has a
de facto lingua franca, and its closest neighbours either speak English majoritarily (Canada) or are not economically impressive enough for its language to be considered prestigious (Mexico). Indeed, as far as I can tell, many Americans think that Spanish is the language of the poor, not the rich, and we know that people learn languages at least in part because of the attitudes they have with respect to the language.
The languages that are already in the USA, such as immigrant languages, are not numerically powerful enough to warrant outsiders from the community to learn them. For example, the Yiddish speaking Orthodox communities. The exception is when the speaker community has the sheer weight of numbers to bring to bear (Miami), and only Spanish has that privilege. And of course native American languages are not even considered relevant for most Americans.
Given these circumstances,
it is perfectly understandable why most Americans need no other language than English. The college students that do study a language will be those enrolled into specialist programs. For example, people who study the Middle East, they would need to learn Arabic or Persian etc.
This is in sharp contrast to most countries in Europe, which are geographically close to each other, and none of them are economic superpowers who are self sufficient like the USA. As they rely so much on their neighbours, that is a strong incentive for teaching foreign languages!
Evidence for what I've said above, can be found in what languages are actually studied most often by European students, which tends to be English and French and German, across the board, as Germany and France are the economic powerhouses of Europe. Imagine if Mexico was as economically powerful as Germany for its population size, and Canada was full of French speakers. I bet you that the USA would be in a far more similar situation to Europe. As it is, I don't think Americans need to beat themselves up too much for not being like the Europeans.
The British on the other hand...have no excuse!
I would love to see the statistics on A level students and their language situation in the UK.