No, because native Mandarin speakers make up only 1% of American citizens.
replyIn the US you are very likely, at some point in your life, to encounter native Spanish speakers with poor English competency. Outside of higher education, you are very unlikely to encounter native Mandarin speakers with poor English competency.
... I'm not sure what part of "If you extend that logic to the world" you didn't understand.
replyThe logic is inherently local.
replyThe typical student does not emigrate or even travel that much, so you don't prepare them to encounter a human randomly selected from the population of the Earth, you prepare them to encounter a human randomly selected from the regions where they are likely to spend their lives.