New Delhi, Feb. 23 -- Ever had the fear of adding an extra zero while making an online payment-at a store, while jumping out of a cab, or at any moment when the ease of "scan to pay" or "tap to pay" collides with our natural tendency to rush?

Mumbai-based financial markets professional Baibhav Mishra, 28, lived through that nightmare last year. While scanning a QR code on his laptop to pay for an order on a B2B marketplace via UPI (Unified Payments Interface), "I accidentally entered Rs.50,000 instead of Rs.5,000," he recalls. Mishra says the marketplace had no recourse for overpaying and advised him to reach out to the seller directly-but nothing came of it. The worst part? "I never even got the item I ordered."

We've been trying to co...