Why India still runs on cash even in the UPI era?

Despite rapid adoption of UPI payments, currency stock in India has more than doubled in a decade, from ₹16.63 lakh crore in FY16 to ₹42.43 lakh crore as of August 7. This is because low-income groups and older populations in rural and semi-urban areas continue to rely heavily on cash. Small businesses, operating on thin margins, also deal in cash.