They don't want to hear anything to the contrary.
I think people are just naturally impatient for explanations and too easily accept the first explanation that seems simple and "obvious". Over the years, however, I've had to troubleshoot a lot of factory equipment that was my responsibility as an engineer. Nothing as sophisticated and complex as the space shuttle, that's for sure. But complex enough to learn that the "obvious" problem was seldom the "real" problem.