Another possibility: it's only moderately hard to do, but government space agencies are massively inefficient. Some reasons to prefer this theory include:
- NASA got to the moon in a decade with slide rules and wire-wrapped guidance computers. It'd be surprising if we couldn't much do better now.
- While large amounts of bloat is tolerable in many public works projects (you can build a dam with twice as much concrete and it only costs double) a rocket can barely afford any bloat. The Space Shuttle pushed the limits of feature creep and bloat so much they could only launch about 4 per year.
- When public projects go down a wrong road, they're structurally unable to backtrack. The Shuttle, the F-135, the Denver airport baggage system, the War on Drugs. If these were projects run by a private company with a CEO, they would've been shut down and re-thunk long ago.
- If SpaceX is right about welded stainless steel being the right tank material (a very surprising claim) it's an example of backtracking that a public project could never manage.
About steel construction: Visually, the Starship looks like a pile of junk. Like someone's Burning Man installation. I think that's inherent in the steel panel construction. You can imagine that, if NASA has started building something like that in the 1970s, the public would complain that it doesn't look spaceworthy. Private companies have the luxury of doing something that looks silly until it works, while public projects don't.