At times the apostrophe is treated like the comma(maybe because they look so much alike?). I think the misconception is that when something's plural you add an apostrophe. Or maybe because it's so small we figure it's better to tag it on there.
We see this all the time in our grocery stores. "Banana's $1.50." Oh so the banana's own $1.50! Not exactly.
Here are the three cases for apostrophe usage:
1. to show possession
ex. the boy's hat
2. to show the omission of letters
3. to indicate plurals of lowercase letters
ex. Nita's mother constantly stressed minding one's p's and q's.
Friends don't let friends overuse apostrophe's. If you love you're friends click here.