You pay for a nice hot cup of ₹10 Chai on the streets but then you got a phone call later on - naively to upsell something, or the next step up, trying to scam you. Unlike me, my wife continues to pick up every incoming phone calls. We have had enough calls from people whom she paid via UPI trying to sell or this/that and what not.
There is a scam going on in India. Random females, who are either naked or scantily clothed, will call up on WhatsApp Video. If you pick up the call, say while in the bathroom and not fully clothed, they will take screenshots and threaten you that they will make that picture “viral” to extort money. I won't be surprised if there is an under-belly of phone numbers and other data being sold that were collected via UPI payment transactions.
Cash is still OK at the tea-stalls, the random shop, etc. Well, when I just wanted to have a simple Bombay’s cutting-chai but the chai-guy wants my phone number, and everything else -- I'm not comfortable with that.