The buyer should not hold all the liability. Regardless of whose fault it is the seller should share that liability. With any purchase the seller is responsible for that item arriving in good condition in the buyer's hands.  Why should eggs or chicks be any different? Many people replace eggs or chicks if damaged or killed during the shipping process. We all know its common practice to send extras in case of damage. There is no rule for that here I assume because it has never been addressed, and perhaps isn't needed at this time. But, I could be wrong.