I�ve come a bit late to this discussion and do not normally get involved in matters of opinion on AB. However, as the founder (and so far only) member of SASA (The Society for the Abolition of the Spurious Apostrophe) I feel I have an interest.
The mechanics of apostrophe usage is not complicated. I was taught it at primary school, probably when I was aged about eight or nine. Nobody reading this should need me to explain it to them. Its misuse is now endemic and has expanded from what was previously accurately described as �The greengrocers� (yes, more than one greengrocer) apostrophe� and it can now be found almost anywhere.
As with many things educational, the blame for their ignorance does not necessarily lie with the badly informed. As has been highlighted in this thread, many educational establishments no longer teach these topics now. A large number of them (particularly at primary level, where things like apostrophe usage should be taught) struggle to provide children with the ability to read and write by age eleven. To teach them correct punctuation and grammar must be a pipe dream for many of them.
People who believe it does not matter are deluding themselves. Many readers will have seen some examples of almost incomprehensible �English� among the questions posted on AB. Bad education, coupled with the ridiculous use of �text speak� make some questions intelligible only to the poser.
Apostrophe misuse alone is not a big deal. Indeed, it is sometimes mildly amusing. Unfortunately it is part of a wider malaise which, if unaddressed, will make this country an even bigger laughing stock than it already is.