FedEx said they delivered my package but didn't. Why do I have to provide a police report to att?

Once fedex reports the package delivered, it becomes your property, therefore stolen from you, not from AT&T.  

It was stolen from YOUR porch, not from a FedEx truck. Therefore, you have to file the police report.

It boils down to your word against the driver's and FedEx sides with the driver. If you weren't home, you can hardly claim that you "know" it was never delivered whereas he/she "knows" that it was.

If they say no, there's nothing more you can do. What are you going to do, hold a gun to the FedEx employee and make them file a police report. 

We don't absolve ATT, trust me, we don't.  The last time I had phone delivered from Verizon, they required a signature.  I had to collect my Samsung GS3 from the FedEx hub the next day because no one was home to sign for it.  

ATT has got to require signatures, its the only way to prevent this.  Meanwhile - order from somewhere else.  Apple, Amazon, Best Buy or any other part of the alphabet that will send a package with secured delivery.

They both did what YOU paid for and agreed to. ATT shipped the phone, no signature required and FedEx was paid to drop it on your porch, no signature required. Not sure what you mean by negligence.

I'm not trying to be "smart". Just pointing out you are in a losing situation. Best thing for your blood pressure and sanity is to just file a police report. That is the quick and easy solution. Why do you want to go the difficult route?

Things like this do happen.  A few months ago, I received an email notification from UPS that informed me they had just delivered a package I was expecting.  I was surprised at the email because, from where I was sitting in my dining room, I had a clear view of my entire front porch... no package.  I also have two dogs who are quite vocal about announcing package arrivals... not a peep out of them. 

I immediately called UPS and explained that I was home, porch was in full view, no package had been delivered.  UPS immediately contacted their driver and, within minutes, called me back to let me know the driver had delivered the package to the wrong address, and that the driver was enroute to retrieve the package and deliver it to my address.  Shortly thereafter, the package arrived, and I received a follow-up call from UPS to verify that all was well. 

Had I not been home at the time, and subscribed to receive delivery notifications from UPS, it's very likely that by the time I realized something had gone wrong, the outcome of my situation would not have had such a positive outcome.