I think you've misunderstood the point of the signature. If they drop it next door, they note which house they dropped it at and also have a signature to show

I think you've misunderstood the point of the signature. If they drop it next door, they note which house they dropped it at and also have a signature to show someone actually took it. The point is not to show that a particular person received the package, but that someone received the package. 99.9% of the time that's enough. If it wasn't and was impacting their bottom line, they'd have started taking photos of recipients by now.