I've hatched shipped eggs about a dozen times now and most of them have been 60% or better hatches. One totally dud hatch in twelve. Two hatches were fewer than 30% went and finished. Luck of the draw. No cabin pressure is an unlikely problem since eggs travel in the exact same compartment as live cargo, like puppies and baby birds. And if it killed eggs it would kill puppies and baby birds in transit as well. It's the responsibility of the airline to live cargo and they rarely if ever blow it because they're liable for some very animal heavy shipments - it would represent a huge liability issue and monetary loss for them. So no, it happens rarely if at all and you'd see it mentioned if any airline routinely killed plane loads of cargo.
Tossing, leaving in the cold, leaving in the sun, playing kickball - the usual postal gorilla stuff is far more likely. An hour in the sun or in the icy wind on the tarmac and you'd never SEE it in the eggs, btw freezing to a significant degree will rupture aircells. And so will a few hours over 120... which you also can't see when they get there.