The idea was not to deliver food (or whatever) over a 10 non-SI-unit distance for 5$, it was to make a short detour to get the food (and a short detour to deliver the food) on a pre-decided 10 non-SI-unit.
Was the idea viable? It probably made two assumptions :
1 - that all people live in dense areas where there would be enough trafic for providing at least one interested driver for any given route at any given time
2 - that human behaves according to financial incentives
The second one is maybe the falseness that doomed the idea...
