I just got two shipped boxes of Ameraucana bantam eggs from two different states. One box was okay and the other was smashed. All eggs were unbroken, but all eggs have damaged air cells.
My postmaster has told me that it matters not at all what's written on the box, other than maybe to the last po worker to handle it when it gets to the destination po. She told me that after being received by the shipper's po, the box is put into a large bin with other boxes weighing up to 70 pounds which is then DUMPED automatically onto a truck, taken to the next stop, an airport or another po, dumped again onto a conveyor belt and on and on.... Most of the way it's all machine sorting, very little handling/reading by a person.
I've shipped thousands of eggs and I buy them too. Something I always recommend, because other than a good packing job, it's the only thing sort of in our control, is to have the destination PO hold the box and call for it to be picked up. Sometimes they won't even do that. But if they do, at least it keeps the eggs out of that final delivery truck and out of any last temperature extremes.
I have also had better luck with eggs air cells if they have come from far enough away that they were in the air most of the time. When they are shipped from just a few hours away, they spend all the time on trucks and get dumped out and sorted repeatedly. I think the vibration of being on a truck is perhaps the most damaging aspect of the whole trip.
I will continue to buy shipped eggs and take my chances. It is still the easiest and often cheapest way to get new bloodlines etc. even if only a few hatch....