That's a good question and I think we might be getting closer to the root of the problem.
If I'm understanding correctly, there was an old system of transit card number recognition which has been replaced by a new backwards-non-compatible system of recognising transit card numbers.
Apparently, Chinese Transit Card numbers can work in both systems, and for some reason Apple have chosen to deliver those to users of older iPhones regardless of what country they live in.
Not being able to use this feature is not a big deal, I was was just interested to find out if there was a something I could do remedy it (other than buying a new phone and hoping that this would resolve it).
Thanks for you help