Sounds like the delivery person signed for it himself.
It's a special service they use for trusted customers only. (Not so LOL?)
I've tried them ALL, including DHL, UPS, FedEX, and my Best Results have been with USPS.
For one thing they Deliver 7 days a week. No weekends off in the delivery holding barn.
The quicker it gets to you, the less time it has to get into trouble, especially over the weekend.
I prefer the USPS Priority 3 Day Delivery service. I purchase an extra $300 insurance. It's the only way I ship now.