The limitations are technical. The device uses a unique card number (so yours is not transmitted) and thus devices can't be easily linked. When using something

The limitations are technical. The device uses a unique card number (so yours is not transmitted) and thus devices can't be easily linked. When using something like this you should know to ask how it works (there are staff everywhere) or check online. Doesn't really seem like Apple of Tfl fault. TfL made it pretty clear how this worked and Apple's tech has limitations due to security. I really don't understand why you wouldn't touch in/out with different devices anyway. Only scenario I can think of is iPhone and Apple Watch users and how many of them are there in London? Seems like a few people had this issue, media picked up on it, and blew it out of proportion.