One big thing the article leaves out is the delivery logistics on the other end of the trip. Let's consider the $5 watch example. For such a low-value parcel,

One big thing the article leaves out is the delivery logistics on the other end of the trip. Let's consider the $5 watch example. For such a low-value parcel, how much time and effort will each party put into delivery/receipt? As a courier, for a mere $5 there is no way I'm going to go out of my way drop off the package to anyone. So the recipient is going to need to retrieve it from me at the airport. Are they willing to wait around for hours (or pay someone else) for me to arrive, clear customs, etc.? Because I'm certainly not going to hang around at the airport for hours for them if I'm only getting $5 - so they'd better be there on time. And that means they are going to have to pay for transportation to/from the airport (usually pretty far from the city center) on top of the cost of shipping. All in all it seems like a pretty hard sell - mail/package couriers have already sorted out these logistics and will deliver stuff straight to your door, usually quite cheaply. The only way I can see the economics working is avoiding import duties in countries where they are prohibitive, which of course means shifting an unacceptable risk to the courier.