It seems more likely that no corporation is willing to spend tens of billions building anything with a lifetime of 50+ years without getting someone to guarantee a return on the investment - see Hinkley Point C:
"The plant, which has a projected lifetime of sixty years, has an estimated construction cost of between £19.6 billion and £20.3 billion. The National Audit Office estimates the additional cost to consumers (above the estimated market price of electricity) [...] will be £50 billion" [1]
Locking in a pricing regime for decades which means consumers will pay £50bn above the market price for electricity? How far we've come in the last 64 years:
1954: "Our children will enjoy in their homes electrical energy too cheap to meter..." [2]
2018: Here's your shiny new nuclear power plant, you'll be paying for it to the tune of £50bn more than the alternatives.
Hinkley Point C is an example of high cost because of many of these same reasons. It is legendary in the industry for high cost.
Mainly these cost are because of the complexity and scale of the project. The licencing and regulation make the complexity and scale larger.
To make mega projects like that efficient you need a trained workforce and that only happens if you build multiple plants.
South Korea for example is building these complex plants at very reasonable time and price. They can do this because they have an industry and trained workforce.
There has been a lot of study in nuclear economics and learning effects are hugely important.
However that means that if a state (France, South Korea) adopts nuclear as a matter of policy and deploys in mass, it can be very cheap.
However for other places I think new nuclear is the only hope. Advanced reactor companies are planning to be much smaller and should be build for 1 around billion.
So yes, people were overly optimistic in the 1954 but we also have to recognize that nuclear technology development was very much hindered by a large number of factors and that we are deploying the same type of reactors now as 40 years ago. This is a sad state of affairs that hopefully will change.
Isn't Hinkley Point C using the EPR design[1], which one might think was selected in an attempt to address the issue of economies of scale?
Having said that, EDF themselves don't appear to be particularly positive about the selected design:
"EDF has acknowledged severe difficulties in building the EPR design. In September 2015 EDF stated that the design of a "New Model" EPR was being worked on, which will be easier and cheaper to build"[2]
A lot of cost is driven by the need to build in a lot of redundant safety features because you are dealing with a fission reaction that can melt down and cause real problems. You also have to deal with and store waste on site. A nuclear plant is a lot more complex than a wind turbine or a photovoltaic plant. Hence it will cost more.
The fact that Illinois and New York had to recently bail out their nuclear plants shows that they are expensive to run (even after they are built!)...
Even assuming we build enough wind/solar to supplant existing coal/gas/oil generation, the unsolved problem is storing that energy for use at night, or on cloudy or windless days. Batteries are the only feasible thing in most places, and they are not available in the quantites needed for such an undertaking, and they are mostly made in Asia.
How much would we need to invest in batteries (mining/refining the raw materials, and actually building them, replacing them as they wear out, dealing with the recycling/waste, etc.) compared to the cost of a standardized modern reactor design.
