MIG wrote

Not having them at Bank would have made Bank an exception, rather
than
the other way round, and maybe the argument was never made.

Far more mysterious (has this been raised before?) are the Carnet
validators, which don't seem to exist at any other DLR stations.
Maybe they are to do with the lifts.

Bank got Carnet validators because of the W&C line which had no
barriers at Bank in those distant days as it still hasn't at Waterloo.

--
Mike D