In message , at 13:12:49 on Sun, 7 Aug 2016,
tim... remarked:
A registered-card only system is going to disenfranchise too large a
set of people (even if they do try to do this on London buses)

Contactless largely undid that.

Not for under 18s and foreigners, it didn't. Especially in groups
when only one between four has a card (which can only be used for one)

And they are the set most likely to be disenfranchised by a
registration system

That was why I said "largely" of course. Registration is not necessary to
use contactless which is why it is available to many if not most
foreigners.

Many foreign countries don't have a credit card culture, at least not
on a one per family member basis

not all foreign banks offer contactless

That's just something that travellers have to cope with, like getting
the relevant foreign currency. You can easily get contactless pre-paid
cards from third parties.
--
Roland Perry