Why not? Why wasn't there a nuclear module (SMR) 20 years ago that can be installed in banks of multiple modules, just like a solar array made of multiple solar

Why not? Why wasn't there a nuclear module (SMR) 20 years ago that can be installed in banks of multiple modules, just like a solar array made of multiple solar cells? Why should every single nuclear plant be semi-bespoke for that particular area? Because the idea was instead a larger standardized reactor to rule them all. Spread the fixed costs per reactor core as thin as possible. This has evidently failed and thus the nuclear industries new thing is "SMR" because lets do opposite and hope we get another 20 years of funding.