New Delhi, Aug. 23 -- Ten years ago, a payments protocol went live across twenty-one banks with little fanfare and a first-month tally of just 373 transactions. Today, that same system, the Unified Payments Interface (UPI), clears more transactions before breakfast than it processed in its entire founding year.

UPI carried 24,162 crore transactions worth Rs.314 lakh crore, moving through more than 700 banks and touching upwards of 500 million Indians. It now accounts for roughly 85% of all digital payment volume in the country and nearly half of every real-time payment made anywhere on earth.

In three decades in this industry, we have not seen a piece of financial infrastructure that has changed the texture of daily life as quickly, or ...