India, April 28 -- There is a particular kind of audacity required to walk into a market already owned by everyone and no one at once. India's used smartphone trade, worth tens of thousands of crores and touching millions of lives, had for decades operated in the comfortable shadows of the grey market. 

Transactions happened often on street corners in Nehru Place, in cramped shops in Palika Bazaar, between strangers on WhatsApp groups and across counters where neither receipt nor warranty was ever a part of the deal. Nobody regulated it. Nobody trusted it completely. And yet, it worked in the way that all informal economies work, by filling a void that the formal world had neglected.

This was the world, a decade ago, into which wal...