What global phenomenon has emerged as a pressing dilemma for politicians from Mumbai to Montevideo, from Tuscaloosa to Fukuoka? It’s not climate change, ideological extremism or economic inequality. No, it’s Uber.

The overwhelmingly successful ride-sharing app is spreading its disruptive technology rapidly across the planet, creating a political crisis wherever it goes in the process. Uber has become a test of loyalties for elected officials torn between important segments of their constituencies, as well as a challenge to their political skills and a complicated experiment revealing their views about the role of government in society. At the same time, it is emerging as a litmus test for their openness to innovation and change. ...