Surfaces like tyvek, boxes, bubble wrap envelopes...those can hold the virus up tp 3 days. Times that by several hundred in and out of the FedEx truck or UPS truck, then times the fact that the virus can live on a plain paper letter for up to 24 hours....and add that regular mail carries can deliver what....thousands in a day?
Then add that said carrier or delivery person could also be asymptomatic and not know they are a carrier...all those packages and envelopes they are touching.
Or, maybe only one particular bubble wrap pack, from say an Amazon seller is covered in the virus. Think then about the carrier who is delivering that package to the house shortly before yours. The carrier who can't wash their hands while driving, or really even use hand sanitizer well while driving...
But he/she coughs or sneezes because it's allergy season and without thinking about it wipes their face and just gave the virus to themselves.
Oh, and add that out here in the country, older people will chat with the delivery person. Or need help up their stairs with a heavy package, Or even will need them to shove a 100lb box in the front door for them.
(I'm a longarm quilter...remember? My machine and frame came via FedEx, the entire system is 350lbs....Five ginormous boxes! The machine alone, in her box, is 92lbs. The other boxes ranged from 60 to 95 lbs)
I get that if you are going somewhere in a car and aren't going in/out of anywhere, then yeah, you don't need a mask just to drive. But delivery people are all about touching things. Things that other people have touched and will touch.
Caution is the responsible thing to do.
I'm cautious about receiving the package/mail. But they need to also be cautious...especially for those people on the receiving end who aren't very cautious.
edit: typos