On 20 Dec, 09:22, MIG wrote:
My hypothesis is that it's an LUL machine there to provide a service
for a very busy NR station that is unusually lacking in nearby shops
that could provide for for the thousands of people who want Oyster
travelcards.

I wouldn't be surprised if that demand wasn't stoked by the presence
of the DLR. In particular, I can imagine DLR passengers used to spend
all day every day hassling the Southeastern ticket office for Oyster
cards and top ups.

U