On Fri, 01 Nov 2013 00:32:06 +0000, Cliff Frisby
wrote:

I don't know whether I am mis-remembering something, but I thought it was
obligatory for a bus operator to issue paper proof that you have paid for
the journey you are making, assuming you don't already have it. The
purpose, I always assumed, was that it protected the innocent passenger
against false accusations of fare-dodging.
[...]
A piece of plastic with the information buried in an embedded chip and/or a
remote computer under the sole control of the operator doesn't provide any
sort of objective evidence, as far as I can see.

I would argue that the proof of payment is still there, it's just in
the card and can be read with appropriate equipment. I don't think
there's any suggestion that Oyster (or other) cards can appear to be
correctly validated as you get on the bus but then show no such
validation when interrogated later... the original post was about a
bus journey not appearing on the web site the next day (I think), and
in my experience it sometimes takes a day or two extra to show up.

Richard.