> It would take at least ten years to educate the nuclear engineers needed to build dozens or even hundreds of them. And even then they don't have experience, they are juniors building very complex multi billion dollar installations.

How did they do it in the past then? The first power station opened in 1956 when the technology was secretive and when there was no internet. The real problem looks completely because of red tape and NIMBY

Edit: You are also misinformed, there are Gen III reactors in operation https://en.m.wikipedia.org/wiki/APR-1400