Ronald,
Not to bust your chops, but you are wrong on both counts. Drainage counts equally anywhere. Rain may fall less or more, but when it does, you gotta get it out of there. It may be that surface slopes can be less, or pipes smaller, but you still have to account for it.
And, I was at a Sandy soil course the other day with drainage problems. The problem is, that over time silt and grass clippings build up in the surface reducing drainage.