You can learn a lot about a place from the public transit. You can tell what the city/state prioritizes, what areas have better funding, and how important tourism is vs how many locals rely on public transit.
Areas with a lot of tourism and an emphasis on that will have signs in multiple languages, or at least in the local language and English. There will be some sort of ‘tourist card’ or day/multi-day pass for sale. The main tourist lines will connect the primary sights and skip past the neighborhoods where people actually live; or they’ll start/end in those neighborhoods and serve tourists for only part of the route. The stops will be clearly announced, sometimes in multiple languages, and there will be signage. Measures will be in place to make the system legible to outsiders.