There are no codes here about concrete being required (either as walls or floors). If you build in flood zone AE "#" you cannot have any habitable space or electrical fixtures below that number and all walls (typically stud infill or screening between pilings) have to be breakaway construction.
A frame house built with a concrete slab on grade is significantly cheaper than that of Rosemary, Watercolor, etc. where you are required to have the first floor elevated a certain height above grade. The concrete wall construction of Alys and parts of Rosemary also increases the costs. While I like the stained concrete floors, bear in mind that that's the finish most of the homes in the neighborhoods the original poster mentioned put in garages. Add at least $5-15 a square foot for tile, wood, or stone floors for a better "comparable".