"IGBTs are used to power every modern electric train, from any number of different countries."
I doubt it's the concept of an IGBT that's of concern here. It would be the various processes and physical dimensions involved in making the wafers and getting a decent yield. That kind of 'secret sauce' means that this particular manufacturer can mass produce the necessary "stuff". It's also theoretically possible that China _COULD_ deny "that stuff" to everyone but themselves, now.
Keep in mind who the Chinese government people REALLY are...
a) they employ millions of people in what can only be described as "sweat shops" but with more modern tech.
b) they pollute the CRAP out of their own cities, because other nations basically pay THEM to do the "polluty" things.
c) a small number of people have the vast majority of the wealth. Most people earn only a fraction of a typical 'minimum wage' in any 1st world country. It is likely that most of the people making iPhone could not afford to buy one, EVAR.
d) they are WELL KNOWN to do "internal use only" knock-offs of western tech, because they have the schematics, board layouts, components, and willing 'minions' to make it happen. "4th shift" it's sometimes called, "off the books" manufacturing of copyright and patent violating stuff.
Given this, and a pile of cash they're _NOT_ sharing with "the people", what do you expect? It's like the royal coffers of the "communist" nation are full to the brim now, and they want to flex their muscles and ensure it *STAYS* that way, indefinitely.
Understanding them means understanding human nature. That government has too much wealth power in too few hands. _ONLY_ corruption can result from this.
And we, in the west, have ENABLED them.