Risk mostly. Many of the vehicles won't be repairable and will just go to the scrap yard. Some will appear to repairable but after some effort end up scrapped too. And some will be repairable but only by guys who specialize in such things and have customers willing to buy a retitled salvage vehicle. For the insurance company, it's not worth the effort and added risk. That someone else can make some money off the missed margin isn't a big deal to the insurance company.