[thenaturalist]

Most likely the same reason as for industry espionage by said countries: Conceptually designing a spacecraft and assuming certain physics properties is a long stretch away from actually manufacturing components with materials that stand up to the stress of a launch.

The “secret” to reliable components which can be produced at scale is very much not generally out there.

[quartesixte]

I will say, some of the techniques that live in the brains of machinists/welders/technicians is borderline alchemy, and sometimes highly specific to the worker themselves.

Can’t really scale that. And good luck doing corporate espionage outside of physically kidnapping them.