Why should it start in SF? You wouldn't happen to live there would you?
But ... but ... but ... doesn't the Earth revolve around SF?! :-P
The pickup and delivery costs don't make sense given the high cost of labor. In India it's significantly cheaper so good to prove the concept out there - at least until drones arrive.
I was genuinely curious. Was excited about p-2-p selling and wanted in on the action but was disappointed. Also, Uber, Lyft etc first started in the SF.
Craigslist is fairly prominent in the US for this use case so it seems like the wrong entry market in my opinion.
It makes sense to enter a market where there are not too many other options for peer-to-peer selling.