LOL, you watch too many movies.
"Signature equals guilt."
Are you stupid? Do you even know what the purpose of a controlled delivery is?
If you got an unexpected package, would you actually refuse to sign delivery confirmation for it? What if it was a gift? Something you ordered and forgot about? Does refusing to sign the delivery confirmation for a package sound like normal behavior to you?
What kind of retard would refuse to sign an acknowledgment of receiving a package? A paranoid idiot who's expecting something illegal.
"Oh gee, he refused to sign, guess we'll call off the raid, he outsmarted us."
Do you think signing for a package makes you "guilty" of something? So you could just order some illegal shit off the dark web and have it sent to whoever and BAM, they'll be convicted?
The purpose of a controlled delivery is to get the contraband into a house, so they'll have probable cause to come in and search. That's it. They'll have to find other corroborating evidence beyond just the package. Proof you ordered it, other related contraband, or more likely in the case of some of the idiots here, a full throated confession.
They don't need a signature. They can hand it to you. They can leave it in your mailbox or on your porch and watch from a distance for someone to bring it inside. These days, it'll more likely have a device that sends a signal once the pack is opened.
Controlled deliveries are done when they don't have sufficient evidence for a search warrant. A signature proves nothing, and in fact, it's an impediment to getting the goods into the building they want to search, so it's much more of a sign it's not a controlled delivery.