I can, because: You need to give them your checking account access. You need to somehow show that QR code, the fastest I can think of on iPhone is getting it

I can, because: You need to give them your checking account access. You need to somehow show that QR code, the fastest I can think of on iPhone is getting it from location-based Passbook notification, which is still way slower than touching my finger to home button. Sure, they won't notice me, but, well, Walgreens got a new customer.