Cashier must explain: No tap. Best case is the customer shrugs and inserts card. Bad case is the customer is confused or argues about it. Horrible case is that the customer must fish through his belongings for a credit card or cash and takes minutes to realize he has neither.
I guess Walmart figured that these scenes repeating daily was not worth whatever its strategy was.
I don't really get how this can be possible. A person can definitely get their card out of their wallet in less time than it takes the cashier to finish scanning their items.
Obviously if the customer is confused then it can take arbitrarily long, but how is a phone less confusing than a card? People don't get to the register only to realize that their card's battery is run down or it's the first time they've used a phone for payments and then they want to stand there for 15 minutes in front of you trying to set it up.