"This, it turns out, really harms the capacity for governments to make decisions that make everyone better off on average but might make any given small region of people unhappy (say, by building a powerplant or a garbage dump)."

Can you explain why? I don't understand this. I would have thought that, for example, given a country of 50 districts, and the decision is being made "shall we build this dump in district 1", you'll get 49 voting yes and the representative of district 1 voting no.