Misuse of apostrophes

Why must people INSIST on using apostrophes incorrectly? In school, some teachers do it, which encourages pupils, especially when copying things down. I have seen an ENGLISH teacher do it. Why must people, for example, in CDs, put an apostrophe between CD and s? Am I the only literate person in the school? I was thrown out of a fruit shop yesterday because I pointed out that a sign was incorrectly punctuated (it read 'Red Pepper's £2 an lb'). Why must I be TAUNTED by such people?

Please, no replies with misused apostrophes just to annoy me.

It is interesting that you use an example of a Fruit and Veg Shop. The people who work in those shops seem to have particular difficulty with spelling and punctuation. Possibly, it is simply that their spelling and punctuation is on public display.

Does it matter?

People are normally only thrown out of Pubs, and Night Clubs.

I found Cyprus to be quite an interesting place for 'English' signs.