> If you have ever wondered why you see basements in colder climates (and conversely more slab-on-grade in warmer ones) is because the bottom of your construction need to be situated under the frost line to prevent shifting caused by the ground freezing.
The other reason I've heard is that many warmer climates in the US are also very wet. Along the Gulf Coast, you basically can't have a basement unless you want there to be an unanticipated swimming pool in it because the water table is only a few feet below the surface.