The biggest costs to nuclear are associated with each of them being unique snowflakes. They need to be standardized and mass produced to bring down costs.
So the dream is many big plants (eg starting 10+ per year), which is what France did and China does, but since we can’t seem to have that here, small reactors are an attempt to solve that.
In 1974, 12 reactors entered commercial operation and 13 more were begun.
https://en.wikipedia.org/wiki/List_of_commercial_nuclear_rea...
The technology was given almost a century to prove itself cost-effective. It did not succeed in the market and only ever worked with truly massive amounts of government subsidies.
High fixed costs + more reactor sites -> more expensive, more nuclear waste sites for taxpayers to clean up
Orders of magnitude more people are killed by rooftop solar, but we haven't raised safety standards on all other sources of electricity to be the same level we require for nuclear.