The object returned late may arrive after the owner’s own plan has already changed.

Lateness has a cost that is easy to miss because it is not the object itself. While something is out, the owner cannot count on it, so the job it was for gets rearranged or abandoned, and by the time it comes back the need has passed. Returning it eventually does not undo the period of not having it.

If you are holding something borrowed, either return it now or say when it will come back. A date lets the other person plan, which is most of what they lost when the thing went out of the door.