And the fact that the distortion is preset and not based on where you click. This is one of those things using heat maps where the clustering is clearly large population centers. Not really as helpful/useful as people think they are
If the analogy to warped spacetime was exact, then there would be a “scale factor” for every point depending on the local transit speed. Then it would be possible to do as this page does and for the answer not to depend on starting point.
However in the real city the transit speed at any point is not isotropic, the space is 3-D, and some paths are forbidden (getting on-off the train between stops).
