A wave of power outages across Indonesia’s Java island has left millions of residents and business owners in the dark, igniting public fury and raising questions as to how the world’s largest coal exporter is failing to keep its own lights on. The answer, analysts say, lies less in a coal shortage than in the rules and incentives governing who gets to buy it, at what price and when. Hours-long blackouts since last week have disrupted the lives and businesses of millions of subscribers of...