Re: the $5 part that blew up the rocket
If you got external accountants and/or business consultants to understand that, well done! Often legal is a safer route, ie explaining where the liability stops if the part fails. Especially given the recent issue of Japanese steel companies faking test results.
But that's why safety critical stuff is expensive. Some responsibility may be offloaded to suppliers, but often not accountability. And if sub-standard stuff fails, there's the potential of very expensive litigation and reputational damage that can very quickly sink the company. See airbags for more info. A cost cutting measure in the gas generator lead to fatalities, injuries and a hugely expensive recall & replacement program. And that was a 'simple' component for cars, not a critical component expected to work in a highly stressed, cryogenic environment.
As well as the strut failure, the NASA report also mentioned that steel cables used as stress members weren't pre-tensioned/stretched, so another component selection issue. But this is why safety-critical stuff is expensive. Not just in design and procurement, but also QA testing to make sure components behave the way they're expected to. Which also applies to re-using rockets, so being able to strip those down and test that critical components aren't fatigued and out of spec.