I guess if the rooms all have windows, it's legal (building code wise) to not have fixtures. There is a general requirement in the building code which states: "All spaces shall be provided with natural or artificial light sufficient to permit the maintenance of sanitary conditions, and the safe occupancy of the space and utilization of the appliances, equipment, and fixtures." In a room without a window, such as many bathrooms, there might not be any way around not having a minimal fixture of some sort for the C of O.