Does no one understand the apostrophe anymore?

Why, WHY when I was at the bus stop this morning did I see this sign:

HUGE MOVING SALE
3/28, 10 am - 4 pm
Ontario Rd NW
desk chairs, faxes, phones, computers, bookshelf's, books, desks, and MORE!

What is wrong with people? Where did they go to school? Bookshelf's?? I would even find bookshelfs less appalling. What's next? Santa's elf's? The First Wife's Club? We must stop this incredible misuse of grammar... I beg you.