This is correct, and it has an impact on local employment and social dynamics, but not at the country level.

> They need fewer people to build and to maintain than older ones did.

That's absolutely not true. Quite the opposite. You do need less people to build and maintain a modern plant than to operate an factory in the past.

Also, you need to clarify what you mean by “older”, because heavy industries have automated steadily between the 50s and the 80s, and that process was mostly achieved by the 90s.

And I can't think of an industry that was still labor intensive by the 20s and that has been more impacted by automation than offshoring.