Just curious, where does this idea that Americans as so non-multilingual come from?
I would actually say American youth deserve a bit of extra 'props' for tending to know at least some of another language BECAUSE they have so few opportunities to use them compared to their European counterparts. In Europe, people get 4-6 weeks off a year (usually paid) for vacation and can travel a couple of hours by train in several directions and be immersed in a different language.
In the US, most people if they get a vacation at all, get 1-2 weeks, and for most it's not paid. Then they have to pay a thousand dollars to fly 12-20 hours just to get to either Europe or Asia where they can just be at the same starting point as their European counterparts. The fact that most Americans learn two years of foreign language in high school even though most don't get the chance to use it, and that then most get minimum another 3 semesters in either that language or another as part of their BA in a country where they really have to go out of their way just to find someone with whom to speak it says a lot for them.
So many of these criticisms of Americans being isolated, or unexposed to foreign languages or cultures assume a lack of interest, yet they totally ignore the economic and logistic realities of living in America versus living in Europe.
If Europeans made as little money compared to cost of living as Americans do, and if they had to pay for their healthcare, education, transportation, and all that like Americans do, and if a vacation/holiday for them was like Americans, something they have to save money for all year, then spend half of it only getting close to their destination, then do that vacation with either no income or greatly reduced income, all the while wondering if they'll still have their job when they get home (because they dared actually take their vacation), then perhaps they too would not quite have the exposure to other cultures they assume is due to a lack of interest on the part of Americans...