answer:It would only sound like common sense… to someone who didn’t have to pay the costs of building an underground city or “doomsday-style” housing. You’re talking enormous expense to forestall what is, really, a black swan event. Aside from which, building underground would still leave land available topside… where people would build because it’s much cheaper. Tornadoes are relatively rare from place to place. Yes, the Great Plains have a lot of them, if you’re counting individual storms, but if the dimensions of Tornado Alley are roughly 1000 miles by 500 miles, that’s still a half-million square miles, and tornadoes are small storms (on the continental scale of the US landmass). So the chances of any one home or town being hit by a devastating tornado are quite low, even though it seems that some town is going to lose that lottery every year, and sometimes more than one town. It would make far, far more sense to encourage people to move their homes from known / demonstrated flood plains. When floods occur those are areas of hundreds to thousands of square miles per event. Even so, it’s hard to get people to change their minds and habits of generations. People get flooded out… and then repair or rebuild on the same spot. That doesn’t make sense to me.