What? They want you to put your phone number on a package tons of postal workers could see? That's ridiculous. I've never been asked to put a phone number, and if I was they'd be out of luck because I don't have a working phone.
It's not ridiculous. They know where you live...
It sure is to me. I don't care that they know where I live, everyone who has ever shipped something to me knows that too. I'm not afraid they'll randomly show up on my doorstep or something. That's incredibly unlikely to ever happen. But its incredibly easy to take someone's phone number and screw with them. Jerks make games out of screwing with strangers by texting/calling them.