As a FedEx driver let me give you guys a couple of hints. You know how you get free two day Shipping or really cheap overnight shipping? Is because shippers like Amazon and/or Wal Mart make deals with FedEx to get really great shipping rates and they renounce to some basic services like delivering packages and getting a signature, etc. So we as drivers can go to your building and just leave the package at your front door without getting a signature and FedEx is not liable for loss, theft or damages.
But before you guys kill me.... we are also supposed to use common sense. As a driver I always try to collect a signature for all my packages and if I have to release a package, I rather go back the next day than to leave a package from Amazon or any shipper that makes it obvious what the contents are. That also applies to weather conditions and high risk areas.