If the oil doesn't cause a problem, why should the maker/manufacturer/blender/seller pay for anything.
If you get coolant in the oil, that isn't an oil problem. If you get dirt in the oil (bad air filtration), that isn't an oil problem.
If the 3rd exhaust lobe on the cam of a Chevy wears prematurely (as it did on thousands of engines) and the other lobes are good, that isn't an oil problem.
If an oil company turns out batches of oil with the wrong additive package, and the stuff gels about freezing--that is an oil problem (Quaker State comes to mind)
If Toyota engines cause sludging because of the engine design, that's not an oil problem.
If the taillight burns out, or a rock goes through the windshield, that's not an oil problem.
If someone has a collectible car, and puts AMSOIL in it, and then files against AMSOIL because the cam is worn--could be a problem. However, when analysis of the oil showed NORMAL wear, obviously the wear occured before the AMSOIL was put it. Suit dropped---
When some cans were mislabelled, and plastic sight glasses in a plant shattered, AMSOIL did pay for replacement, line flushing, new fluid. (Kept the customer)