The world’s cheapest data costs have done wonders for India by helping spread the benefits of the internet beyond a tiny, urban, affluent class. But there’s a problem: Successive governments have hounded telecom operators with outlandish financial demands. Now things have gone too far. Vodafone Idea Ltd., one of the three private-sector competitors left standing in what used to be a field of a dozen players, is very close to crumbling under the weight of its $30 billion debt. That will effectively turn the wireless market in the nation of 1.4 billion people into a duopoly.