Roads tagged highway=pedestrian+motorcar=destination are currently not routable using the car profile. Ideally this should be routable.

http://osrm.at/f5s

The wiki definition of access=destination is:

Only when travelling to this element; e.g., local traffic only.

If any of the routing points are at an element with access=destination, it should definitely route as the user intends to visit that point and not drive by.

cc @TheMarex