1) Access the phone - if you're not a moron, you need to type a PIN/password
2) Launch the app
3) Enter the app password (it does access your bank account, hope it has a separate password...)
4) Ask for a QR code (hoping connectivity works, and you're not roaming)
5) Hope nobody calls you in that very moment <G>
6) Scan the code.
sure, fingerprint readers and other technologies can simplify some of those steps, if you trust them. Roaming charges may be also an issue if you travel a lot.
1) Get the card
2) Plug the card (if it is not contactless)
3) Type the PIN
Moreover card payments are usually made over interoperable networks using common standards. I.e. Italy uses the "Bancomat" system, which is a consortium not controlled by a single entity, and is broadly supported both by banks (and the likes), and payment systems (POS and automatic systems, ATMs, highways). It would take a lot of time and money to replace all those systems with QR reading ones, and I'm not sure it would become more user friendly, using a phone to pay still looks clumsy to me. It looks to me more a useful backup feature if your card no longer works (or is stolen or lost), than the primary system.
Maybe because unlike many I don't walk looking at a phone in front of me...