Well, the US government, more specifically a branch of Dept of Homeland Security, doesn't have some innovative gadgets that detect drugs as they come in through UPS and FedEx. As a FedEx shipment comes in to an airport, you have a couple of CBP officers who either randomly choose packages to open and search, or look through the description of the object and the package and see if something is fishy. For example, if a package is coming from Amsterdam and it's supposed to be a stamp collection, best believe the officer will be suspicious of it and open it up.