Except people don't want to live underground. And considering that in that area of the country, at certain times of the year, you can dig down with a shovel for an hour or two and hit water, making those homes waterproof would be expensive.
Its a good thing tornadoes this huge dont form down in Louisiana. We would be fuuuuuucked.
Lots of small ones form though. This area gets a bunch. but they are usually really weak. not even EF1.