This particular article is talking about Facebook Messenger chats being scanned. The link you provided is talking about public Facebook comments that anyone can see, and in fact the kid was reported by a third party, not some shady surveillance company.
This article is terrible, but the original article has been pulled off the local news site. It wasn't on someone's Wall, it was in a message to his friend.
Your article doesn't say anything about chats being scanned.
> Jack Carter said a woman from Canada saw the posting, did a Google search for his addresses and when she noticed he lived near a school, called the police.
I don't think that was a chat being scanned. The article even states that a woman in Canada saw the post and called the police, it was probably just on his wall.