The article seems to base the cost per sq/ft on the selling price of the homes rather than the actual building costs. If a builder is able to shave a bunch of

The article seems to base the cost per sq/ft on the selling price of the homes rather than the actual building costs. If a builder is able to shave a bunch of costs during construction but does not pass those savings on to the home buyer (instead just pads their profits), then the study would not reflect economies of scale in construction. Homes tend to be priced at what the market is willing to bear in relation to what other similar homes in the area are selling for; not what it actually cost to build them.