Body shops do not need a license or training to do collision repair.
Barbers and hairstylists need a license to cut hair, but shops don't need one to cut up and weld a car back together and send it off to an unsuspecting customer. Here, all you need is a business license, and there are no inspections. The body shop technician decides how he is going to fix the car, and nothing is forcing him to research the correct method and stick to that plan.