It's a positive story they tell, making it unique. They urge the reader to understand that economic effects of this sort take time and generally have a considerable lag to the corresponding cause.
Electricity is an earlier example and parallel in American history.
Eventually, it had an unfathomable effect on productivity. Mercifully, both authors are journalists for the Wall Street Journal and that has put them in the habit of writing in the vernacular. Prosperity is at all times comprehensible, intelligent and certainly not dumbed-down for the mass market. In the final chapter the authors argue that the federal government could help ensure the coming middle class prosperity. This should bring everyone with libertarian sympathies to the edge of their seats.