London’s system, often credited as a world leader, doesn’t do concession fares via contactless. It’s either entirely free with a pensioner card, or a student card needs topping up online. For contactless to be linked to a person, I’m curious how those work with cards on phones/watches (which are different numbers to your plastic cards); and it already sounds like a customer support nightmare waiting to happen.

yeah it'll be some kind of registration. In the lab they showed me how to check the number within Apple Pay, so it's do-able. Whether concessions is world-leading or not rather depends on when they deliver it!