While it is true that they now sign on the recipient's behalf to avoid contact, the recipient has to be present and they have to ask for their name (in case they don't know the recipient well).

I don't know, but the contractor's story sounds suspicious. It is not the first time that iPhones or tablets go missing and that they say there was somebody who opened the door when according to the recipients it was not true. I still think it's his responsibility, not eBay's or the seller's. I mean, if nobody yelled to leave the phone at the door and the contractor says somebody did, then obviously something does not add up.