my friend wants to know
Ask your friend why his friend doesn’t know how to use capital letters or periods. 
Because theirs lots of non-English first language people on them they’re intarwebs, and there lack of grammar skills shows.
Or possibly they’re all greengrocer’s.
There and their?
To and too and two?
Ironic and sardonic?
Right and write?
It’s the age of txtng. y bthr 2 rite rite?
People who are writing something that will wind up on the Internet tend to feel their writing should be excessively colloquial in tone and formality. They take that belief so far that they are unconcerned with using the correct word if it’s clear from context, as it usually is, which is appropriate.
Your friend seems to be a most inquisitive person. This is a common meme from you.
Moving this to IMHO, where you can get opinions to this.
samclem Moderator, GQ.
Carelessness.
And the fact that its an easy mistake to make (see? :p), and the fact that, in respect of comprehensibility, it usually does not matter a damn.
This might be a whoosh, but anyway…
I think this type of error is actually more common among native speakers than people who learn English as a second language. English is a second language for me, and there are aspects of English that are difficult to learn, but this is certainly not one of them. They are only confusing if you learn the words by sounds alone at first as a child, and then you’ll have to learn when to use the correct written form later on in school. For non-native speakers though, more often than not, its and it’s, or two, to, and too, etc, are entirely different words with different pronunciations in their own language. It’s not difficult at all to map them into the correct written form in English.
I think this is correct. The same is true of French – errors of confusing two homophones are very common among first-language speakers (fermer instead of fermé for “closed”), but much rarer among second-language speakers, who make different categories of errors (non-idiomatic usages and errors in gender and agreement).
There is a huge difference between “know” and “care” about the difference. Usually, the meaning is clear either way, so it doesn’t really matter.
Its complicated.
It’s monkey see, monkey do; if people see other people doing it, they think it’s correct.
Most people never bother to learn the difference because they think they already know.
as/like
that/which
who/whom
meat/meet/mete (ok, i’m having fun)
Because it’s always been an arbitrary orthographic convention that not many people have fully internalized, which is furthermore inconsistent in at least one branch with an otherwise exception-less general orthographic convention which many people have fully internalized, and because now, with the Internet, there is much great exposure to non-professional, non-proofread writing from random strangers than ever before.
Using an apostrophe is a pain in the butt. Especially, when in a hurry and speaking informally.
I often post during short gaps at work. There isn’t a lot of time for formalities.
Missing letters reinstated in bold. It’s minor enough that I’d normally just let it go, but in a thread like this…
Are you trying to say the differences between the words are indistinguishable?
The reason is obvious: you don’t have to be literate to own a computer.
I suggest that if it infuriates you as much as it does me that you post this and this every chance you get. It might piss them off, and of course you have the jokers that intentionally do it wrong thinking that they’re funny (we have a few in this thread already), but do it anyway on the off-chance that they might remember the next time.
I was just going to say it’s because possessives that end in s take an apostrophe in some people’s minds. It’s the same reason people write student’s when they mean student’s.
Oddly enough, I have rarely seen yours affected…
And yet it seems that using “it’s” when “its” would be correct is at least as common as the inverse mistake - probably more so.