Think of it this way. If you buy a ticket you can show the ticket and it’s valid even though you never provide proof of identity, and the person checking is just verifying that the human entity in front of them have a piece of cardboard. No problem there. Buying a ticket with Apple pay just puts the “cardboard ticket” in your phone.
Now you could also buy a monthly travel card, and register it to your identity, which is great because now if you forget the card, but can prove your identity then no problem, since they have the records.
The issue here is that she has a non-identified cardboard ticket on her dead phone. Which doesn’t enjoy the benefit of being tied to her
Identity.
Apple pay isn’t really any different from the coins4cardboard tech here. If you buy a cardboard ticket with a credit card and throw it away, then you can’t show bank statements to get out of a fine. The expectation of the cardboard ticket is that you keep it on you to prove you have it. If that had been the case and she’s dropped a ticket out the pocket of her coat, would they be blaming the coat brand?