It doesn't work also in countries like USA. (I think we agree.)
And it doesn't work in other countries where the security is not so tough like Argentina. [Hi from Argentina!]
It's not exactly the same case, but ... from: http://www.nytimes.com/2013/03/10/magazine/the-professor-the...
> [...] but when he arrived at the airline counter, he was greeted by several policemen. Asked to identify his luggage — “That’s my bag,” he said, “the other one’s not my bag, but I checked it in” [...]
The question that needs to be asked is "Is Airmule one of these companies, and are Airmule couriers authorized representatives of Airmule?".
The distinction is not that Airmule is a company that provides services in the manner of a common carrier. It's whether they're recognized as such by the government. This is probably done by filing papers in the US and in China. Then they could answer "We are a common carrier, license number XYZ. Users sign form ABC to become an official Airmail representative."
A slightly less important but still relevant question is whether operating a courier service using an airline which itself offers the same service is a violation of the airline's TOS.
As the article says, it doesn't work like that in countries like China (and I suppose it doesn't work like that in many other countries). You're 100% responsible for the package you're carrying unless this happens:
> One of those exceptions is to be the authorized representative of a “common carrier.” These are companies like FedEx, UPS, or DHL, or the airlines themselves
So, as the article says, if someone decides to fill your bag with heroin up to the top Airmule will have nothing to do with it, the death-sentence will be all yours.