I am not trying to say that things couldn't be designed better. They could (that is never _not_ true). But it is also important to remember that this was a crazy accident as well and several uncommon things had to go wrong at once. The reactor was designed to withstand 100 year earthquake and tsunamis (that's equivalent to flipping almost 7 heads in a row) (we're also not accounting for the odds of the tsunami). But what I am suggesting is that there is a limit. Sure, we could foresee 100 heads landing in a row, it is certainly possible, but at the end of the day you have that end up with an acceptable amount of risk. I do not think 100 year events (1:99 probability) is correct as climate change is changing those odds, but it isn't like this was engineers being lazy and dumb. You are using post hoc analysis to justify actions made without that knowledge. As they say, hindsight is 2020. I do want to remind you that this was the largest earthquake to EVER hit Japan. That's much harder to predict and extremely reasonable to believe such an event is unlikely during the expected lifetime of the reactor.

Economically cheaper, but that isn't the only factor that we're discussing. We're also talking health and environmental.