I think it is because non-native speakers all learn the same basic 1000 words (initially) and same most-frequently-used grammatical patterns. Native speakers kn

I think it is because non-native speakers all learn the same basic 1000 words (initially) and same most-frequently-used grammatical patterns. Native speakers know thousands more words and all the colloquial phrases. I can understand foreigners (Americans, anyway) speaking Chinese pretty easily, because we all know the same (limited) vocabulary and grammar. I have real trouble with native speakers because they use all the short forms of the words and the grammar patterns that you don't learn initially.