When you tap in with Apple Pay on the TfL's network in London (e.g. enter the Tube), the transaction goes to the issuer for authorization. In the case of Amex, they - unlike Visa - charge you £0.10 at the point. If you decide not to travel (e.g. due
to service disruption/cancellation), that charge seem to remain... I don't recall seeing that charge when I use my real Amex card.
I complained in my
previous posts on Apple Pay about inability to pre-authenticate myself via TouchID
before the transaction, so that during a rush hour I can go through the Tube gate without any delay. That function IS available: simply open your Passbook, select the required card and place you finger on TouchID. That puts the phone into "tap
ready" mode (which, oddly enough, does not time out as long as Passbook remains in the foreground. What's currently missing is the ability to do that without unlocking the phone, i.e. direct access to Passbook just as you can do with camera, clock, calculator
and torch. My bet is: that function is coming.
BTW, pre-authenticated Apple Pay is almost as fast with the Tube gates as Oyster card. Apple Pay works even better as it can be used at a greater distance (10-15cm).
Stay tuned for Apple Watch feeback.