Good luck with getting German tourists (and no doubt many others) to
pay this way :-)

There's very , very many more knowledgeable people posting here than
this occasional tourist but I can't recall using a staffed ticket office
for the underground or equivalent as a tourist when in Paris, Budapest,
Boston, New York, Hong Kong, Sydney and Tokyo. In fact I can only
recall *seeing* staffed ticket offices in Boston and Hong Kong (and the
latter IIRC because we were looking to buy an Octopus at the airport).
Are other systems really still in the land of cash, wetware and language
barriers?
--
Robin
reply to address is (meant to be) valid