I suspect the claimant is suing the car owner because the family knows the owner can’t afford a long civil case whereas the dealer has more resources (insurance) for acts caused by idiot employees. In other words - suing the car owner will be easy money.
If the owner can’t afford a long civil case then he probably doesn’t even have enough money to cover the plaintiff’s legal expenses to pursue the case. Surely he isn’t going to have $15M to his name.