I was just reading the Environmental Impact Report for rebuilding a Safeway supermarket in Oakland, and it does in fact have a section about predicting whether

I was just reading the Environmental Impact Report for rebuilding a Safeway supermarket in Oakland, and it does in fact have a section about predicting whether the store will "blight" any other nearby retail areas by drawing too much business away from them. (They conclude that it will not have such an effect, even though there are already vacant retail spaces right across the street from the Safeway site.) But just because the studies are done doesn't mean people will make the decisions that optimize everybody's lives. Every town wants the tax revenue from a new big box store, even if it means destroying the retail economy of the next town over.