I beg to differ. If I rebuild something, the liability is all on me. If I install a part using accepted methods, the liability can be spread out to the vendor.
Keep in mind I spent nearly 20 years telling big corporations how to avoid environmental liability, and one of my best friends is an attorney and is also the guy who got me into Rovers. He has agreed and endorsed this policy for these reasons.
I have neither the deep pockets, nor the same level of insurance a dealership has. AND, I'm very risk averse when it comes to the safety of my clients.