>I don't understand why FedEx and UPS can't do this.
Amazon can be reasonably certain that the consignee is also the person that ordered the package, and they have that person's phone number. FedEx and UPS do not have this luxury. I've called numbers for alcohol deliveries (Under no circumstances can I release the package to a neighbor or just leave it) and instead of the consignee I was put through to a winery out in California. Thankfully they got in touch with the customer and had them divert the shipment before I had to return to sender the package.