I understand sat nav, and I also understand that the time and distance for a route can be different for traversing a road one way or the other, or for traversing a junction one way or the other, and even depend on time of day or location traffic at the time.

But for walking directions that does not apply, and I would expect a walking route A-B to be the inverse of B-A.

So WTF does apple send me one way to get there and another to get back?