I'm going to weigh in here as someone who has never shipped eggs (yet), but has bought an amazing number of them this spring.
Yes, in the end, eggs are definitely a "Buyer Beware" item. There are many things that can affect hatchability, from the age and nutritional state of the layers, to the postal handling, incubating, humidity, etc. etc.
I have had hatches that were great, and hatches that were dissapointing, and a very few where I didn't get a single chick; which are the most dissapointing of all. My son and I obsess while hatching, constantly checking the temp, etc. It is funny... I don't think either of us realizes that we walk past the bator all the time and yell out current temp and humidity level, as a normal part of our walking through the house routine.
I have my postman put ALL boxes inside my house, eggs or not..... there is even a large permanent sign on the door, telling them it is unlocked and boxes need to be put inside, thereby eliminating the "cold" factor.
The only time I would ever even question the eggs is when a large number start to develop and then they all die prior to full maturity. Even then, I will generally only let a seller know as an "FYI" that I got an entire batch of eggs that failed to develop to term. I have never 'expected' replacement eggs; however, when I get 12+ eggs, and not a one hatches I think the seller should know. I will also try and let the seller know when/why they didn't hatch (broken air cell, 7 day and dead, 14 day and dead, etc.) I've had a few sellers offer to sell me more, and at that point, I've generally declined, especially on the really expensive eggs. I don't ever mind paying shipping, because that is only right, but if I've already dropped $50 - $75 and not one has made it to hatchability, I will try and find another seller of the same breed. I have also always chatted with other folks who bought at the same time to see if they had similar or dissimilar results. That will also weigh in to my decission on whether I will purchase more eggs from that breeder or will try another instead.
As to wrapping and boxing, I have been AMAZED at the variations that I've encountered. Most are very good, but some are outrageous. I had one who wrapped each egg in a small piece of foam, and then placed all of the wrapped eggs, loose, on a larger sheet of bubble wrap and pulled the corners together and taped it (like a laundry bundle!) Then that was placed AT THE BOTTOM of the box, and peanuts were dumped on top. The eggs that were on the bottom of the box were shattered, the eggs that were toward the top of the bundle were better, but out of 12 eggs, 6 were smashed, and the box did not appear to have had rough handling. On the opposite side of the spectrum, I got a box in the mail recently that was ripped open, the Post Office had put the contents back inside and taped it shut and stamped the box "Damaged when arrived at H------ Post Office". I figured that I was gonna open up a box of egg soup, and not so much as one egg had a crack in it, and only one aircell was broken! So, we'll see what actually makes it to hatchability. on that group.
By and large, I think that the sellers on BYC are an honest, reputable lot. I would much rather take my chances at BYC that on
eBay or Eggbid, although I have bought from both of those sites as well.
My 2 cents.