Maybe not a right but more a commitment for governments towards public transportation. Not having a car makes everything so much harder. Having as much coverage as possible within reason, more buses and drivers, expanding metro lines. Right now in my city it is just “bearable”, I am at least grateful I can do things like see buses on the map and transferring to trains is easy. Was much worse before! Not like governments wouldn’t be able to make their money back, and imagine how many less car crashes and traffic clogs we could have. Not to mention the environmental benefits.
Also electric buses are cool. So quiet and can charge in them.
Edit: To elaborate on why it should be a right: it is not like in the olden days when you could walk to the store or your job. Everything is simultaneously dense and far thanks to how zoning works and cities being car-oriented. The right to mobility exists in America, but what if we took it further and made sure you really could go where you wanted without having to invest in a car?