For several hundred years stairs have had 1″ thick wood treads on each step. Recently some floor contractors have been installing plank flooring on steps. For steps that are open on the sides this almost never looks good. One reason is that the trim needed is not available in the color of the flooring. Floor guys usually don’t do skirting on the walls or other things necessary for a quality stair job. We regularly come across very poor work by Flooring installers on stairs