Its not just the end carrier, here. Yours might be understanding, another may not. But they are the end of the line.
When the eggs leave the hands of the producer - they embark an a journey of destruction unequalled in their lives for trauma. Consider that most things that go though the mail are NOT fragile in the extreme, as are eggs. They really are an exception and one that isn't built into the system.
The focus is on speed, getting everything sorted and on its way in record time. This sorting and stacking and movement is done primarily by machine - the human touch is applied only little in the process. There are vast movements where your package doesnt see the hand of man. That does not lend itself to gentle treatment.
All the marking in the world cannot sway the sympathies of a package handler working on a piece production quota, high speed belt or robotic pallet stacker. It isnt that the PO is deliberate in its mistreatment as much as it has little opportunity to care, one way or the other.
Expeditious delivery is actually in your favor and I totally agree with holding your packages at the PO for pickup. Thats one less chance for damage and an inconvenience worth dealing with. Styro Peanuts, wrapping in egg cartons, individual bubble wrapping and good labeling are next in the battle to get them to you safe and viable. After that, it is in the hands of Luck.