International mailing costs are quite high. In this situation you must also expect to pay for someone's time to obtain a suitable mailing box, package up the phone carefully, complete the shipping label and customs form, and take the package to the shipping company. When you call upon a commercial shipper to do all of that, you will indeed pay through the nose.
The actual shipping costs would almost certainly be lower if the package were taken to a post office for mailing, but in that case someone would be making a dedicated trip to drop it off and stand in line, on top of buying the box and doing the packaging. The extra labor cost of a dedicated trip to the post office would be significant, and not too many companies would want their employees running such errands--thus SuperShuttle's plan to outsource the whole project to FedEx.
Edited to add: Earlier this year I left my European-trip rain jacket somewhere in my hometown--probably the only time I had ever used it in the US. I didn't realize it was missing until my departure day, at which point I couldn't even remember when I had used it or where it might be. I am seriously considering sewing email-address labels into all my outer garments.