Most buyers do understand that they are not buying guarantee of healthy chick hatching. Rather what is bought and sold is the 'Potential or Chance' of fertile egg being healthy/viable enough to hatch.
What is tricky is that this viability is a continuum of health or robustness that is affected by shipping. This is in addition to it being a fresh and fertile egg before shipping. What decreases this potential/chance is:
1. time spent in the shipping process,
2. packing/positioning.
Its a mystery how the box is handled but what is in control of the seller is optimizing freshness , packing, day of shipping (to decrease time in postal) and possibly even waiting out a severe weather day. Eggs that arrive after just one day in a sense will be more valuable than those that arrive after 4. As we can go by odds. So in this sense a buyer already has a loss if the eggs arrive with shipping delay.
By the way, 'when its shipped' is important too, much like with other products but here too there can be bit more as seasonality affects egg value. There is supply demand difference here. A good seller if post dating delivery time more than about 10 days should use the words 'Pre-order or Presale' in the title.
So understanding the above can give us some guidelines:
Example I: Eggs arrive on time but are broken and box is damaged- Solution- Seek funds from post office- this can be seller or buyer. If eggs are valued more than 50.00 the seller should of bought insurance for this passing on cost to buyer in the shipping costs. But this can provide buyer with reassurance and add value to the auction.
Example II: Same as above but value was 120.00 and only partially insured by postal. Noone thought of adding insurance. So seller did there part basics anyway but didn't mention or offer insurance although it didn't cover damages. Buyer did their part , paid straight away with correct address but hadn't inquired about insurance. There is slightly more onus on seller here as they are more of 'expert' as seller and moreso should of raised the issue. For remaining uncovered loss I'd split the burdon- seller gives 60% of the remaining so in this case would be 42.00 refund
Example III: Eggs arrive within reasonable to good time -1- 2 days shipping speed and from within a relatively close seller. Box looks excellent and eggs are well packed and appear to be in good condition. Purchase was for 4+ eggs. Buyer follows best practice, sits them to help air cell definition than about 18-28 hrs later they go into well tested incubator which is closely monitored for temp and humidity. A few days later , no sign of fertility. More waiting, couple days later , there is 0 development or say less than 40 to 50% showed any development.-- Ok, so what are the expectations here? Surely its profound luck to get 12 out of 12 though it does happen. Generally I believe the understanding is that 80% is very good 70% common and adequate/fair, 50% mediocre but passable - below 45- 50% a poor hatch. Here I think with less than half fertilized with buyer able to reasonably explain their procedure, should result in half to full refund (depending on fertility). If 0 eggs fertile should be full refund.
Example IV; Same as above but Seller very far away. And buyer would/should expect it to be 4+ days No refund or small partial refund- seller discretion. EXCEPTION:: Seller in one of those postal rural zones yet USPS is listed as 2-3 day priority (but its near always actually longer) and seller doesn't disclose that it will likely be an additional day or ships end of week making transport time take 4+ days. Here Seller should refund due to non-disclosure of exceptionally long typical ship speed due to their address. Ideally ebay should have shipping alert when locations flag USPS delivery over 3 day time/speed.
