It'd be great if we native English-speakers would tolerate — and even encourage — "mistakes" in English to streamline (refactor?) the language and make it easier for non-native speakers to become fluent: + The world would be better off with an easy-to-use, global lingua franca. + For historical reasons, both good and bad, at the moment English is the logical candidate. (The use of an alphabet also supports English as…
> "it's" as a possessive
are mostly native-speaker exclusive. Your/you're, there/their, etc. spelling mistakes you just don't see non native speakers make. This is because they're just that, spelling mistakes.
So while native speakers know what they mean but it's just associated with a sound in their head, they just write out that sound. Non natives on the other hand usually think about the grammar, the right word, etc. I don't think I've ever met a non-native speaker that makes the there/their mistake e.g.