Insurers do deals with repairers to pin their costs down. Some of these complain loudly about the lack of profitability of their businesses. But the relationships between insurers and salvage companies and accident management companies and credit hire cowboys have become very strange. Manufacturer repair schemes are largely more understandable and cut out the dirty business. Basically the car insurance business in the UK needs to be completely ripped apart and for the whole thing to start again. But that will never happen because car insurance is compulsory and all the smart brains are concentrating on the potential for rip-offs.