They simply didn't take into account all of the associated costs and complexities that would be involved with the actual nuclear power plants, not to mention the political and social complications.
That doesn't mean such a future can never happen, it's theoretically possible. We're simply in a place right now where it's hard to imagine with our current level of technology and our current energy economy.
The regulation is basically a liability shield and subsidy, the industry wants more, not less, of it to build plants.
And if wishes were horses .... It's hard to imagine how any democratic society could have gotten past the salience bias to make that happen. (Also, there's the better-the-devil-you-know familiarity bias working in coal's favor, to say nothing of the political influence of voters depending directly or indirectly on coal for their livelihoods.)
EDIT: This also brought to mind the trolley problem [0], with the added wrinkle that it's not possible to predict with any confidence which specific persons would actually be injured or killed.
Are African and Latin American countries with less effective governments and less regulation are leading the world in innovation, cheap nuclear power, genetic engineering and so on?
A casual disregard for the living and a "happily ever after" fairy tale correlates pretty well with a lot of cult and religious behaviours, and associated human tragedies, but not very well with actual happily ever after, I think.
Restating it isn't convincing. Innovation didn't stop when slavery was banned, innovation didn't stop when Romans mandated that bread sellers sold a fair amount of bread, or when weights and measures were standardised in commercial transactions, or when mains electrical devices had to be earthed/grounded/double-insulated.
"You can't pollute groundwater with careless discharge of nuclear waste" - innovate within that constraint.
We shouldn't be rewriting history now that we see that nuclear power could have actually prevented global climate change.
...and the fact we have about 4bn more people here than we did in 1960.
So, no, population (at least high population) isn't something that was unforeseen.
Energy is free: we have a fusion generator that runs 24/7 with no maintenance and is so powerful it can burn out your retinas from 150 million kilometers away.
Hypothetical: if aliens started building a Dyson sphere around Sol, could we stop them?
This was also at a time when nuclear fusion energy was theoretically possible but before half a century of research has labeled the problem 'very hard'.
If federal mortgage rules empathized solar, you’d see near free energy production in residential in a decade or two.
He also incorrectly anticipated that atomic transmutation of the elements would become a bigger trend than chemical rearrangement of existing elements.
"It is worth emphasizing that the main trend will be systematic exploration of nuclear reactions — that is, the transmutation of elements, or alchemy rather than chemistry."
As for why he was mistaken about nuclear power, it's possible that he was extrapolating from the fantastically rapid progress of nuclear weapons technology. Fission was demonstrated in 1938, the first chain reaction in 1942, the first fission weapon in 1945. The first megaton scale thermonuclear explosion was demonstrated in 1952 and serial production of thermonuclear weapons began in 1954. Between 1944 and 1954 the explosive power of the largest military bombs went up by a factor of roughly two million [1] [2]. There was a 2300-fold leap from Grand Slam to Little Boy (6.5 tons TNT equivalent to 15 kilotons) and another thousand-fold leap from Little Boy to Castle Bravo (15 kilotons to 15 megatons).
The challenges of making useful power reactors for electricity production are much different. Civilian power reactors have to compete with other electricity sources on cost. They have to produce power for decades rather than a fraction of a second. They are expected to fully contain fission products rather than disperse them widely as fallout. Recall that at the time of this writing, 1955, no country had yet built a power reactor comparable in output to large coal or hydroelectric plants. There had only been some small demonstrations like the 2 megawatts of electricity produced by the BORAX-III reactor. The actual difficulties to be encountered at larger scales were not yet known.
Finally, "affordable" electricity was a moving target. In constant dollars, large American industrial buyers were paying 40% less per megawatt hour in 1970 than they were in 1950 [3]. Concerns about acutely hazardous air pollution were not yet widespread enough to justify a cost premium over fossil-generated power. Widespread concerns about greenhouse gas emissions were even further off.
[1] https://en.wikipedia.org/wiki/Grand_Slam_(bomb)
[2] https://en.wikipedia.org/wiki/Mark_17_nuclear_bomb
[3] https://www.census.gov/history/pdf/histstats-colonial-1970.p... - page 827
I am wondering why this prediction is so off given how other ones are spot on? How the situation back then made John von Neumann believe it, and what happened differently, moving this into the realms of fantasy.
Perhaps if an another effort of a scale of the Manhattan Project had happened, the concept of the "free energy" would have been more realistic.