I just skimmed the video of Starship assembly, so everyone please forgive me if I'm misrepresenting it. But it looked like some parts of assembly and stacking were being done using general-purpose construction equipment. Naturally almost none of that would be acceptable in the development of any other crewed space vehicle, if done under the auspices of a NASA contract to do so. Now you can apply whatever judgment call you want to. But this is part of how SpaceX is able to move so quickly. And corner-cutting was honestly what delayed them in the ability to bid on many U.S. government contracts. Obviously this raises the question of whether the controls and oversight that persist in competing programs is really necessary, and whether it really achieves the safety and quality goals that crewed space flight requires. If anything this provides more data that helps us ask and answer these questions.
They seem to be building their prototypes on a sandy, wind-swept shoreline, using cherry-pickers, big hammers and crowbars. It's fascinating watching them.....I nearly coughed up a lung when the rolled a $3 million Raptor engine under SN8 on the back of a pickup. They then used what looked like a butchered work platform to (jerkily) raise the Raptor up to install it on the thrust puck.
The same with loading SN9 onto the test stand.....a huge crane, some slings and two blokes on a couple of monster cherry-pickers. Boeing would have a stack of Statement of Works, Risk Assessments, lifting plans etc as high as the booster. However the ultimate end was the same, namely a booster on a test stand. Guess which one was completed first?
Their building process is the very antithesis of the hyper clean room assembly that you see elsewhere. And yet, they have made more test flights in a year than NASA/Boeing have with the SLS in 10 years.
Which approach works the best? Time will tell. I'm guessing that SpaceX are doing it this way so they can learn as fast as possible. Why make everything fancy when the chances are that it will end up in a pile of scrap? Once the design is worked out then they can crack on with making it look purty. They clearly know the process of building human-rated craft, so I am assuming that they will apply that set of knowledge once they work out how to fly the Booster and Starship.