i think its mainly the trust factor and some cold war/ego issues as well. many people in the usa still think the rest of the world has a corrupt and inefficient postal system where things are opened or stolen at will.
even the UK? I now have an amusing image of Postman Pat tearing open peoples letters and parcels hunting for NOS bike bits. Actually...
To be fair never realised it was such a hassle to ship from the US. Shipped plenty to the US and worldwide myself. Never had any problems, even on a frame.
How much is parcel2go Jezza?