If this was happening on a regular basis without my consent then i would take it up the mail carrier in person to work out a resolution. In the event that did not work then obviously we would go up the chain of command. Luckily my mailman and i grew up 5 houses apart and have known each other for 50 years, he will call me ahead of time to let me know.
I have a funny story about this type of thing. I live in a fairly rural area with only 1 neighbor, on a closed street. I work from home. So when I'm not here, I usually get back home within an hour, max. My mailman signs for me, but always texts me first to make sure I'm okay with it. It's great. I don't worry about it and I totally trust him. Heck, I even get him a Christmas present every year. So earlier this year he meets me at the mailbox and says, "John, you know these USPS scanners have GPS in them, right? The office can see exactly where it is at all times. So.... I have a golf lesson that'll take about an hour. You mind watching my scanner till I swing by and pick it up?" LOL! I was more than happy to. He's done me favors for years. So this year he's working on his golf game a little. And I'm more than happy to cover for him.
Too lazy to get out of the truck, huh? I once had a substitute driver honk the horn till I came out to sign. She didn't think she should have to get out of the truck, I guess. It wasn't even raining!
I've had postal carrier sign for me a few times, it doesn't happen often and all the times it did, I was at the door and handed the package with the worker saying they signed for it & I OK it. The worst is when I get a sub who doesn't even come to the door or even drop a small package off in the box itself, they will put a "missed you" notice on the door or in my box, even though I was home or it was small enough to fit in my box, which is secured. THAT is my biggest peeve.