Hmm, I use Walgreens for all my scripts so I have a Walgreens card. Currently you have to either wave your Walgreens card or enter your phone number and press lookup. Then swipe your card, then press the cash back option, then press the 'do I want to donate to XXX cause, then press is this amount ok. So I wonder if Apple pay will eliminate any of these steps? If not then it's not really easier.
I love Walgreens because they are everywhere and I have had the need to use one in different cities in the past. But their pay system is a real mess as it is. It will be interesting to find out. Frankly I don't have an iPhone (I have a nokia 920) but if using Apple Pay streamlines Walgreens that would almost be enough to make me buy a new phone!
It will be interesting to see if Walgreens does streamline the pay process with Apple Pay. If Apple Pay only replaces the credit card swipe then it will not really improve the pay process for Walgreens since as you point out you still have to enter your walgreens card, yes or no for a cause, tap ok on the screen etc.