Shipping cannot cause an egg to go from fertile to unfertile. It can kill the embryo though, especially with temperature fluctuations. Rough handling is not good either.
When the hen develops the yolk she puts the blastoderm on it. If that egg is fertilized the embryo starts developing. The hen’s internal body temperature is perfect for incubation to start and it takes about a full day for that egg to make its way through her internal egg making system. The embryo is alive and starts growing. That’s why you can see the bull’s eye after the egg has been lain. Even if the embryo dies due to handling, temperature, age, or something else the bull’s eye should still be visible when you crack it. Fertility is not the only thing that can cause a clear egg. If the embryo dies the egg will be clear.
A shipper cannot know for sure whether any specific egg is fertile or not when they ship it. They obviously cannot open it and look. You do have a reasonable expectation that the eggs will almost all be fertile. The shipper should be incubating eggs to see that they develop or at least opening some to look for the bull’s eye. If most of the eggs they open have the bull’s eye the assumption is that most of the eggs they don’t open will also have the bull’s eye. Even when I hatch my own eggs I get some clears and I normally have one rooster with seven hens. Even commercial hatcheries with experts managing the chickens for fertility get some clears.
