Um, i haven’t taken a poll or anything, but i’d guess that it’s laziness.
Mikefule brings up an excellent piece of psychology though. I often have that problem with the ‘is’ and ‘isn’t’ thing, but, if i’m not sure, then i refer back to the rule, over and over again. Eventually, i remember it and no longer make the mistake. It comes down to whether you care that you’re wrong. I, personally, am not a big fan of being wrong, so i make an effort to correct myself when my wrong is brought to my attention.
Really? You’re saying that if you always wrote, “I will neaver ‘learn’ to spell”, and people constantly told you that it is spelt ‘never’ because it is a conjunction of ‘not’ and ‘ever’, being “n’ever” and then ‘never’, you wouldn’t eventually learn the proper spelling? Either i don’t understand your inability, or i just have more faith in you than you do. You seem to spell fine (finely?) to me, and you even understand the difference between ‘then’ and ‘than’, (the former being a sequencing and the latter being a comparison, people). If you had specific, unambiguous rules for all spelling and grammar, and always had these rules available to you, then i’m pretty you could go without making a spelling or grammar mistake (typos excluded) ever again. I think that everyone can ‘learn’ to spell and use proper grammar, if they wanted to. It all comes down to will.
I also think that most people could learn to spell and use proper grammar a lot better than they are currently doing so, without needing to have to refer to literature for rules all of the time. I’m sure that they could memorize the rules pretty well on their own. Of course, there could be the case where learning some new rule makes you forget an old rule, and, therefore, you’re stuck in a never-ending cycle, but other than that, yeah. I think there’s a Homer Simpson quote there somewhere, but i can’t remember what it is.
So, in my view, the way to learn to write properly is to first be notified when you are wrong, and then to have the will to correct yourself. The first step, thankfully, is what people have been doing for others. Thus, my original defence of them. The second step is up to the people whom (‘whom’, right, because it’s part of the predicate?) are making the mistakes. Insulting, still, has no place in this process, though.