So the technology that looked good, theoretically, in 1970 may not have the same outlook in 2020.
In particular, France's failing attempt is the EPR. There have been construction starts at three sites, and all have been massive off schedule. For the three not in China, they have been massively over budget. The build in China was the third to be started, but is the only one completed; planned construction time was 48 months, but it ended up taking twice as long. I don't know how to judge the pricing of construction in China, but if the Western world could do it in 8 years and at the stated cost of $7.5B, it would be a fantastic deal.
What has changed since the last time? I don't know. Maybe different sorts of people go into the same jobs. Maybe executive culture is to blame. Maybe engineering culture is to blame. Maybe procurement and construction is to blame. Nobody has provided a solid explanation of X, Y, and Z with concrete examples.
Some will say regulations are different and the cause, but at the same time nobody says that these are unnecessary regulations, or that there's a smarter path that would make them cheap, it's always just vague accusations without any specific call to action.