Separating "regulators" and "manufacturers" in such distinct categories is overly simplistic, I'm afraid. As we saw with the whole Boeing debacle, the manufacturers are the experts on what they build, and we expect them to give clear, levelheaded, and honest guidance to operators and regulators. That also means they must have some responsibility for the outcomes of that guidance.

Having a separate regulator, which does no building themselves, somehow maintain a separate team of independent experts is a fools errand. We should of course have independent evaluators, but the people building the thing are the experts on the thing.