I've had 2 bad experiences with Amazon orders, and USPS was to blame for both. They put the envelope/package in the wrong mailbox in the apartment complex I live in and marked it as delivered. I've received other people's mail in the past too...
Amazon's customer service has been exceptional, they send an overnight replacement with UPS and required a signature.
Recently, Amazon opened a pickup location near where I live, and I've been shipping more expensive items there. The pickup process takes less than 15 seconds. Literally, walk in, scan barcode, locker opens up, and I pickup my package.
Can't wait for Amazon to own the entire vertical and optimize the living shit out of it.