The Cartesian coordinates can also be misleading, since even on foot you can't go in a straight line between any two points. There could be a fence in the middl

The Cartesian coordinates can also be misleading, since even on foot you can't go in a straight line between any two points. There could be a fence in the middle. There's also a difference of height. It might take 10 minutes just to get from an underground station to the street level right above it, and you can't go in a straight line there either.