> in India, thanks to UPI you can pay anybody if you know their phone number
Not true. You need the UPI ID of the person, which may probably be phone@bank or phone@paymentsbank. If you assume that everyone is using only Google Pay (or Paytm or PhonePe or Amazon Pay or pick another provider), then those providers would know the UPI ID to connect people to for payments. For people who don’t use these payment services but do have a bank account (say, HDFC or SBI or ICICI), there’s no way you could pay them only by knowing their phone numbers without knowing the bank they have the account with and the bank suffix they use for the UPI ID.
Not true. You need the UPI ID of the person, which may probably be phone@bank or phone@paymentsbank. If you assume that everyone is using only Google Pay (or Paytm or PhonePe or Amazon Pay or pick another provider), then those providers would know the UPI ID to connect people to for payments. For people who don’t use these payment services but do have a bank account (say, HDFC or SBI or ICICI), there’s no way you could pay them only by knowing their phone numbers without knowing the bank they have the account with and the bank suffix they use for the UPI ID.