You're assuming that the parents had collision insurance on any of their vehicles.  Usually it's the lender that requires insurance -- the dealer doesn't care, once they collect the full purchase price.  There may be a state law requiring liability insurance, but that's not what this question is about.  

There's no law requiring insurance on your home, if you don't have a mortgage.  Many people in Florida are already making that choice.  Likewise, just because most people insure their vehicle against loss, at least if it's worth more than a couple grand, doesn't mean that everyone does it.  Especially if you have a teen-age driver in the house.  The mistake is letting that kid get a license in the first place (we don't know she did), and then giving her the keys (which seems to me to fit the definition of "this is not a business vehicle").