No it does not, BF's can not make a seller purchase insurance but it can and will hold the seller responsible if the package does not make it to the buyer and the seller just assumes the buyer is out their money.
I've saw to many threads where the sellers claim they are not responsible once they drop the package off at the P.O., as far as I'm concerned they are responsible and that's why it's highly recommended that the seller purchase insurance unless they plan on paying out of their own pocket for a lost package.