Who's this "we"? The general public and politicians have learned absolutely positively nothing. The engineers could talk your ear off if you're willing to listen, about solutions that will never be permitted to be applied.
I mean seriously, looking at the disasters we've had, pragmatically noting the engineers have not been given free reign to fix existing plants or build newer safer plants, at least in the west, there is no way anything short of space alien invasion could shake "us" into action.
For example, you build a plant designed for thirty years of operation, invent a safer way to do things twenty years after the old plant is built, then operate the old plant unchanged for fifty years for financial or environmental protest reasons. Then act all confused around year fifty when something blows up that was a known and fixed problem thirty years ago but can't ever be implemented.
There are numerous source code / programming analogies relating to sunk cost fallacies and political footballs and the like.
Its not just the engineering department. From a pragmatic crisis management standpoint some CYA civilian cultures should not be permitted to operate reactors. Military combat crews universally have more effective crisis management techniques than even the best civilians teams, even cross culturally. To say implementing this management shakeup would be tricky would be an understatement, however "we" do know that some cultures just can't operate a plant without civilian CYA-ing themselves and their neighbors quite literally to death. Civilians in high positions are trained by the system to prioritize protecting themselves personally from future court cases over accomplishing the overall mission of not melting down the plant ... the plant will take care of itself, at least it always has so far, and prioritizing themselves is how civilians rise to positions of power ... put them in charge of a crisis and it melts down and everyone dies ... somewhat more gung ho military personnel will do things like dump raw seawater into a sub reactor to prevent a meltdown, even if it results in a guaranteed economic kill of the reactor, even if they have to improvise. If you grab the tiger by the tail you will get eaten if you text message blamestorm over who's responsible and who wrote what proper procedure instead of holding on tight to the tail. You can't just engineer safety into something and call it done, anymore than you can checkbox security into a web application and call it done.