Imagine there are two planemakers, each has a computer system to record when they removed the door bolts. One company uses it 95% of the time while the other uses it 100% of the time.
For the market to assign a different price to those companies, shareholders have to be able to tell which is which.
Investors cannot tell. The official reports don't include anything that wasn't officially reported. People who know first-hand have insider information, and are forbidden from trading on it. Shareholders have no power to enter the assembly floor and carry out spot checks. And "independent" auditors like Accenture are even bigger clowns than Boeing themselves.