I'd actually go the other way around. I see a lot more value in getting smaller public transit systems onto a common standard. Getting set up to use public tra

I'd actually go the other way around. I see a lot more value in getting smaller public transit systems onto a common standard. Getting set up to use public transit as a visitor to a top tier city like New York, Brussels or Montreal (I can't speak to London) is easy. Usually they have explanatory signage and staffed kiosks at all the major intercity transit stations. And good websites that clearly explain what visitors need to know to navigate the system. It's visiting a city with a lower-tier transit system that tends to pose a greater challenge. I'm thinking here of cities like St. Louis, Milwaukee or Portland. Stations may not have attendants, automated kiosks may not be well-maintained, websites tend to be ill-designed or be missing key information about how to use the system, etc. And, on top of all that, I'm not necessarily visiting there often enough to amortize the (already relatively high, due to the aforementioned problems) cost of getting to know the system across may visits. And I certainly don't want to have 15 different transit apps and payment accounts to juggle. Standardizing the fare structures and payment systems could be a big boon to visitors. There's potentially more value to the the smaller transit systems themselves in standardizing, too. None of them is individually a large enough system to achieve good economies of scale w/r/t the technical and administrative costs of maintaining their own special snowflake fare system.