As a recent example, last month I was in Henan, as well as Shanghai for a day.

No one ever gave me guff about using cash -- I believe everyone is required to accept cash anyway. However, it was irritating at times trying to buy a metro ticket in Zhengzhou and Shanghai, because either A) the ticket machines would only do QR codes, B) the time-honored bugaboo of coin-only machines, or C) my new five kuai bills were "too new," to quote a Shanghai Longyang Road metro station worker. For all scenarios, I'd have to bop around the station, looking for an attendant to sell a ticket. Flimshaw.

OTOH, trip.com made HSR purchases neat, but Chinese stations are still a bìtch. Needing to show my passport (which serves as the ticket) thrice, restrooms still reeking of cigs, barely any (if any) snacks that don't contain cornstarch/garlic/some vague powder, and worst of all, the inevitable scrum and/or maze just get into the train stations ... I suppose the half-full would just nudge me on the shoulder and say, at least we have HSR.