Echoing others' points about not requiring people to own smartphones to get around the city. But more than that, the physical signs are superior to smartphone

Echoing others' points about not requiring people to own smartphones to get around the city. But more than that, the physical signs are superior to smartphone feeds in many ways - we already have situations where people are milling around outside stations fetching the status feed. Crowding is a severe problem with the NYC subway, and a sign that you can just glance at while walking is much more efficient than having everyone stop and check their phones.