In the 1950s, A&P supermarkets (remember them? You probably don’t) had a 75 percent market share. What used to be the General Motors Building near Central Park South has an Apple store where the automobile showroom once was. When Kodak loses customers, it withers.

But when government fails, it expands even faster. This is, Gillespie and Welch say, because “politics is a lagging indicator of change,” a sector of top-down traditions increasingly out of step with today’s “bottom-up business and culture” of: “You want soy with that decaf mocha frappuccino?”

A generation that has grown up with the Internet “has essentially been raised libertarian,” swimming in markets, which are choices among competing alternatives.