27 dead in US tornadoes. Have they heard of housing codes over there?

It's tragic to read of so many people killed in yet another devastating tornado season in the US. But when you see pictures like this of homes torn into kindling it really makes you wonder about housing regulations in the US...

Darwin was similarly wiped out by a cyclone. But within a couple of years, serious cyclone rating regulations were introduced for all new housing right across the northern half of Australia.

And it has paid off.

So what's going on in the good ol' USA?