I would dare to say that native speakers are
not the only model English learners may follow;
of course, they have acquired the language and
hence, they are supposed to speak it properly;
but it is also true, that talking a language, does
not mean managing it to a whole extent. As it is
well known, spelling and grammar are some of
the weak areas of native speakers; while foreign
language speakers are taught, basically, in terms
of the grammar and the right writing of a language.
This is the way we “understand” their language,
whereas they just “hold” and “use” it without knowing
special features of its language.