"Could of" instead of "could have" being a prime example among native speakers. Although it's shocking how many people genuinely believe the former to be correct.

> I would guess that those who have learned the language have a more logical, grammar based structure and write more deliberately.

We have our own native languages with their own idiosyncrasies and we don't make mistakes like "could of" or "you're/your" in those languages. There's just no excuse for those simple mistakes...

Greek has 5 very common and 1/2 rare spellings for the sound 'i' (as in 'kit'): ι, υ, η, οι, ει /υι,ηι

Imagine if people who can't tell you're/your and write 'could of' had to face this reality... They are lazy ignorant people and the other native speakers need to stop enabling them and making excuses.

<edit>

I'm not actually sure if 'ηι' exists, google is showering me with irrelevant results.. in any case, furthermore, there's

two ways to spell 'e' (as in bed): ε, αι

two ways to spell o: ο,ω

two ways to spell the av/ev sound: αβ/αυ , εβ/ευ

two ways to spell the af/ef sound: αφ/αυ , εφ/ευ

and more. Maybe the difference is that all this crap makes you actually pay some attention to the language if you don't want to embarrass yourself

As a native German speaker, who is basically at the same level in English now, I also started doing these weird mistakes native English speakers do. I never had this issue in German not sure what it is about English, I think it's just the random spelling vs pronunciation in English. Your brain just can't keep up matching your vocal thoughts to the right spelling when typing quickly.