Apart from fishing around for change, I find nothing inconvenient about cash. You pay the cash and you’re out in seconds. There’s a consistent experience between different Merchants when you pay with cash. There’s no dependency on Internet connection, literacy level of Merchant staff, and any other external factor (apart from demonetization!).
I find TAP & GO credit card payments even more convenient than cash. For the uninitiated, these are the PINless payments enabled by the latest NFC contactless credit cards on NFC-ready POS terminals. However, if the Merchant does not have a landline Internet connection, then the POS works on mobile Internet connection, which tends to be patchy these days, and causes delayed or even failed payments.
I find mobile wallet payments extremely painful due to patchy mobile Internet connections at many Merchant Establishments these days. Because my payment doesn’t go through instore, I often come home and make the payment. Then I have to take a screenshot of the payment confirmation screen and show it to the Merchant on the next visit. All this is very time consuming and extremely inconvenient for a time poor consumer like me. Besides, mobile wallets have a strong dependency on battery, GPS, literacy level of Merchant staff, and so on. Ergo, I find cash more convenient than mobile wallet payments.