disclaimer: I only read the OP
I have noticed a drop in hatches in my customers over the last two years especially. That is when I started to add "Please do not X Ray... Live Embryos" to the outside of the box. So then I thought, "Maybe it's my birds" and yet still... new flocks, young birds, flocks with 1:2 hen ratios even... all had bad results for buyers but great results for me.
One thing I think I will change next season is stop writing on the outside and also find a new way to pack. I use pine and in hindsight... a box of pine is suspicious.
Still, on the other hand, I would still buy hatching eggs myself. I just understand that they hardly ever all hatch.