How can it be in possession of the body shop and them not being responsible for securing it?
Depends on a few things.
If the car is insured against theft, that insurance has the primary responsibility.
If not then, the shop liability insurance might pay. That can depend on the shop insurance tho.
A customers car was stolen from my shop, from a fenced yard and inside an area that had a security system. The customer did not want to report the theft and risk his insurance premiums going up. He asked me to pay,I turned it over to my insurance. Then the lawyers got involved.
My understanding is that since the property (vehicle) was insured, they had primary responsibility, I had no liability (my coverage) as long as I had taken reasonable care to secure the vehicle.
Besides the order of liability, his insurance, then mine if he had no insurance. My insurance company argued successfully that where he lived had a higher rate of theft than where my shop was located, and that he often left his car in less secure areas than behind two locked gates with a security system. At work, the mall, restaurant, driveway at home...
Since I provided more security for his vehicle than he did, I was off the hook.
The way the insurance liability was explained to me was that once the vehicle, the property, was insured for theft, that company has primary responsibility. For anyone else’s insurance to become involved, they have to be proven irresponsible in the care of the vehicle, then their liability insurance kicks in. My insurance against theft or damage to a customers car, is a form of liability insurance.
This also protects the owner of the car. If he has a $500,000 car or $1,000,000 motor home and I only carry a mandated $10,000 minimum, his insurance company can’t weasel out of paying.