Umm, assuming you have the same opinion as grandparent comment, you don't want google tracking your payments but you'll happily trust google's pinky promise about your fingerprint being stored only on the phone?
I personally find using a plastic card more convenient than fumbling for my phone and unlocking it (I don't use biometric unlocking as it's not protected by the 5th.) It's also easier to go somewhere without a phone (yes, it's possible) when you have a card on hand.