Paul Corfield wrote:

I agree some ticket products - particularly group ones - can be rather
complex. However I do struggle with the apparent resistance of people
not to get an PAYG Oyster card even if it does involve payment of a
deposit. I had an Octopus card for HK for many years even though I only
visited every 1-2 years. It took seconds to get it checked and
re-enabled if it had become blacklisted through lack of use. Similarly I
was in Singapore last Christmas and about my first purchase was the E-Z
link card for MRT and Buses. You pay for the card *and* a deposit *and*
travel value but the convenience factor far outweighs these costs in my
view. I didn't surrender it before leaving but will keep it for a return
visit.

Once every major city has one it will be pretty difficult to keep up for
world travelers. Especially if they are not enthusiasts who enjoy
keeping such things.
--
Michael Hoffman