Thinking about this, I think what happens if we take it to the extreme - a system that lets a single user enter his route to work - and compare how various transportation systems, including innovative ones, would impact his day to day.
It's really hard to build such tool, and if it's done well and made appealing to users, it could be the base of a political tool for people to pressure their representatives to implement new and better systems and improve voters lives.
For example, Tokyo Metro has many out-of-gate transfers, where the user taps out of special gates (Ikebukuro M/F) and into another paid area (Ikebukuro Y) on the same fare, as long as it's within 30 minutes. There are also out-of-gate transfers between different stations, such as Shintomicho and Tsukiji. Beijing has transfers within the same paid area that are notorious for being long and/or congested, so much so that some believe it's an intentional traffic control mechanism. These all have significant implications on actual experienced commute time and fare.
So if the end goal includes human navigation or commute statistics, it's incomplete without such considerations. Those government APIs you're using are only concerned with ridership and not these details. Short of visiting these places, you could watch vlogs (there's probably 5 for every Tokyo Metro station), and you could perhaps simulate some routes on existing navigation systems.
I'm assuming this text is an AI hallucination because there are dozens of rail operators in Tokyo. Tokyo Metro is not even the largest and basically only operates an underground subway. JR (Japan Rail) operates above-ground and is much larger (and nation-wide).
https://en.wikipedia.org/wiki/List_of_urban_rail_systems_in_...
Just a single line of JR East's (Yamanote) moves a third as many people daily as Tokyo Metro does all by itself, and JR has over 50 lines just in Tokyo.
Edit: I've had my coffee now, and see what you mean. the API exposes it at /api/systems/{system}/lines/{line}, as well as aggregate for the system at /api/systems/{system}, working on supplying distance unit in api response now.
But it seems to be just an API with a website sporting a terminal font. What am I missing?
London, Paris, Copenhagen, Rome, Madrid?
I guess it takes a while to add each new one in.
Your best bet for most of Europe are the open data platforms. Example for France: https://transport.data.gouv.fr/. There's soooome standardisation around a few formats:
GTFS, Netex, SIRI along with their various extensions (like GTFS-RT for realtime data), etc. Just parsing these (which is already a large undertaking in and of itself) should get you covered for a bunch of networks.
Oh, also, much of the data you'll find, especially from smaller cities or regions, is awful. You're going to be told that the line icon is white, on white text, and that's actually perfectly normal because actually their bus header is from an obscure system from former Yugoslavia that actually interprets "0xFFFFFF" as black when on layer 1. Good luck!
