>>4 here.
I wasn't inferring that native English speakers are stupid or anything like that, just that they - or at least 99,99 % of them - cannot pronounce any other sound-/word-constructions but those that exist in the English language.
There might be two reasons for this:
1) The language is constructed in such a way that its pronunciation is too different from other languages, making those other pronunciations hard to learn after having grown up with English only.
2) Whereas pretty much every country in the world but USA and UK get alot of linguistic influence from other languages, be it in the form of TV, radio, tourism, travel, etc., USA and UK hardly has any of this, as far as I can tell.
If you look at Japanese, for example, they are even worse at learning new languages than English-speaking people, even though they have a lot of English everywhere. Why? Probably because their entire pronunciation system consists of the kana tables, and thus they find it hard to pronounce anything but the sounds within that system.