Energiewende didnt start in 1973, it was first authorized in late 2010.

France's nuclear program was also very, very expensive: https://www.i-sis.org.uk/The_True_Costs_of_French_Nuclear_Po...

You can say whatever you want when discussion the cost of nuclear in France because of the structure of its nuclear industry. Part of it comes from the government’s budget, so depending on your point of view it can be accounted for differently. Then, there are externalities (pollution, greenhouse gases, etc). And then there are strategic aspects and associated costs. The alternative in the 1970s was skyrocketing oil, which is much more costly at the planet’s level, and was on track to be much more costly at the country’s level as well. And in the meantime, consumers got reasonably cheap and clean electricity for decades.

Skimming your source, I would not trust it very much.