I think postal employees get a lot of bad rap due to others not knowing exactly or anything about how mail gets from one place to another. Postal employees do not handle our mail from one point to the next, all alone. There are other human beings who help along the way. There can be truck drivers, there can be loader drivers, there are cargo handlers... for anything to get to where I live, it goes thru all the above and the last portion is loaded onto an airplane and then off loaded, put in a truck, most times its a flatbed type truck so everything is literally outside but saran wrapped and then off loaded in the heated postal annex. This leaves a lot of room for error in regard to shipping live chicks!
When I ordered bantam BLRW chicks and GLW LF chicks, I did not order enough to keep them warm thru all the above so when they arrived, only one of each was limp, not stiff like the others, and none were breathing. I posted this before, but I began rubbing their chest and backs, gave them CPR, put their heads in my mouth and lightly puffed as they are WAY smaller than a baby, and got them breathing on their own. Then I put them in my bra, making sure they did not get crushed and could still breath while warming their body temp and once they seemed they had a minor chance of living, I put them under a heat lamp but still had to constantly hold them, like a mama does for any type of offspring. Constant touch keeps a thriving baby, no touch and no will to live...those two made it. Now I've got a daughter/pullet chick from the supposedly BLRW bantam but that original chick turned out a reddish buff with a white tail, possibly not BLRW- her chick now seems to be feathering out as a BLRW even though that is not what her daddy/roo is
All the above is why there is usually a limit to how many you can order at once, such as at least 25 but even then, there is no guarantee they will survive all that above...its just too bad all the postal employees all over, get the blame in the end, they are only the ones that deliver to your final destination while many other hands and machinery have "helped" along the way.