

In the same way that Americans speak English.
Sure, their language is mutual intelligible with English, but if an Englishman comes over here and asks for some chips, they’re going to get a bag of crisps. They’ll mess up verb conjunction on a bunch of collective nouns.
And bless the souls of my Australian mates who come here and call everyone a cunt.
Literacy is also about English (at least as commonly reported in the US). About 1/3 of functionally illiterate adults in the US are foreign born. I have never seen literacy stats that measure “literate in any language”.