China is building US and EU designs of reactors at a fraction of the costs in the US and Europe.

Your examples of regulatory asterisks are on the design side of things. I don't think that the cost of capital for Vogtle & Summer in the US, or Flamanville and Olkiluoto in the EU, were excessively high. As for your 3rd point, there were tons of adjustments during the build of Vogtle, which is a big reason for its large cost overruns. Regulation didn't necessitate those changes, they were all construction bungles.

Which I think leads to your point 2, construction competence, being the primary cause, which aligns with everything else I have read on the subject. For example, another poster pointed to this paper:

> We observe that nth-of-a-kind plants have been more, not less, expensive than first-of-a-kind plants. “Soft” factors external to standardized reactor hardware, such as labor supervision, contributed over half of the cost rise from 1976 to 1987. Relatedly, containment building costs more than doubled from 1976 to 2017, due only in part to safety regulations.