The majority of those unionized employees in China belong to government-controlled unions. The Chinese government has the last word on all this, and the employees’ “rights” are ultimately subject to the CCPs whims. Basically both the company and the union are ultimately controlled by the same entity.
It’s absurd, as it defeats the whole point of a union.
This is what eventually seems to happen under every attempt at communism that we’ve seen so far.
Keep in mind most of that machinery nowadays is made by workers elsewhere in the world, primarily in China, where the union membership rate is something like 45%.