Here in Central Florida many builders offer optional bonus rooms rather than basements. Bonus rooms are typically constructed over the garage and in some cases over several bedrooms in the back of the house. Basements are a problem here because during tropical storms the water table can rapidly increase above the ground level causing ponding or puddling which is a form of flooding. Builders will typically fill in the area where ponding occurs to raise the elevation of the slab, preventing ground water from entering the house. That said during my search for a new home I was shown with two houses with walk out basements. One side of the basement is excavated into a hill and the other side accessible to ground level through standard or sliding glass doors.