There might be a survivorship bias here. You will have travelled to large cities with public transport because those are the most viable places to go if you can

There might be a survivorship bias here. You will have travelled to large cities with public transport because those are the most viable places to go if you can't drive. If you want to go to places that are remote/not got tourist infrastructure with buses (e.g Vietnam et Al) then you'd seem somewhat stuck. TL:DR A lot of the world is not located in metropolitan cities.