but apparently there is a serious worldwide shortage of egg hens.
Not a chicken vs egg, which one came first thing. The eggs are not fertilized and egg laying hens lay 300+ eggs a year so if there's a shortage of eggs, it's really a shortage of hens. The reason(s) for that, I haven't a clue.
“The reason for that I haven’t a clue.”
It’s because of the trend and laws mandating pasture raising.
When they opened the cages to let the chickens on the pasture, as mandated, all the chickens crossed the road.