But this is slightly different to the situation which I described.
What happens if there are two station, one of which has a machine
which is designed to take only cards, and another station has a
machine which is designed to take both cards but due to some defect is
not able to take cash at that time? The facility then provided at
both stations is effectively the same, though while one machine is
fully working it could be argued that the other one wasn't. A
passenger couldn't be expected to know in advance what type of
machines were installed; they might never have used that station
before.

The son of somebody I know was challenged on a train for not having a
Travelcard. He replied that there was no facility to buy one at the
station where he boarded and was then told that there were newsagents
etc. not far from the station, and he should have gone there to buy
one before boarding the train.