The website for Moore, Okla., recommends “that every residence have a storm safe room or an underground cellar.” It says below-ground shelters are the best protection against tornadoes.

But no local ordinance or building code requires such shelters, either in houses, schools or businesses, and only about 10 percent of homes in Moore have them.

Nor does the rest of Oklahoma, one of the states in the storm belt called tornado alley, require them — despite the annual onslaught of deadly and destructive twisters like the one on Monday.

It is a familiar story, as well, in places like Joplin, Mo., and across the Great Plains and in the Deep South, where tornadoes are a seasonal threat but government regulation rankles.

In 2011, a monster tornado razed large parts of Joplin, killing 160 people in a state that had no storm-shelter requirements. The city considered requiring shelters in rebuilt or new homes but decided that doing so would be “cost prohibitive” because the soil conditions make building basements expensive, the assistant city manager, Sam Anselm, said. Even so, he estimated that half the homes that had been rebuilt included underground shelters. Schools were being rebuilt with safe rooms, he said.

In Moore, the website explains that the city has no community shelter because a 15-minute warning is not enough time to get to safety and because, “overall, people face less risk by taking shelter in a reasonably well-constructed residence.”

Curtis McCarty, a member of the Oklahoma Uniform Building Code Commission and a builder himself, said the twister Monday would have defeated attempts to resist it above ground. “You cannot build a structure that’s going to take a direct hit from a tornado like that that’s going to stand,” he said.