Some people aren't actually primary practitioners of English while others are simply to lazy. Also some people use their phones like I am doing at the moment, and I usually end up editing my post because a few autocorrect errors always occur.
It is the internet...so some people just don't care :s!!!
I just got used to it. If I made a mistake on spelling in one of my classes it's 5 points off. Taken advanced classes for a good while, just got used to it quickly. Can't say I care enough to try to display my intelligence to people (I used to say that).