That’s not true. They are physically massive, incredibly complicated machines with all kinds of large scale pressure welding, forging, containment systems, 100s of miles of plumbing, and other serious large scale engineering. They will never be anywhere close to as cheap as something as dead simple & mass manufacturable as solar.
If they were intrinsically costly, they would have been costly in the U.S. in the 1960s, or in France in the 1970s-90s, or in South Korea today. It is because of regulatory ratcheting, and the effects of that (both direct and second order), that costs escalated.
NPPs are intrinsically Big Projects. The western world is almost universally suffering from Baumol’s cost disease - we cannot build Big Projects at a reasonable price anymore. Subways, bridges, NPPs, you name it - all cost many multiples of their inflation adjusted 1970 cost. And that’s before they inevitably blow their budget by 2-3x. Until you can somehow fix the labor / housing / management cost issues NPPs will not be affordable, even if you relax nuclear specific regs.
Mass manufactured things like solar and wind turbines do not suffer this.
Since the 1970s, large construction projects have been layered with several major regulatory regimes that didn’t exist when most affordable infrastructure was built. In the U.S., NEPA (1970) dramatically expanded pre-construction environmental review and litigation risk, causing planning timelines to extend by years. Around the same time, OSHA began rapidly increasing the degree to which workplace processes were regimented, which permanently increased labor-hours and limited on-site automation.
For nuclear specifically, this was compounded by post-Three Mile Island regulatory response. This increased the tendency to use bespoke designs, i.e. discouraged standardization, which prevented automation and the benefits of learning curves. That's why Baumol-style cost dynamics took over.
This same pattern shows up in subways and bridges. It’s not that 'big things can’t be built cheaply anymore", it’s that we changed the rules under which big things are built.
