I was trying to find some Cornish hens at Walmart today - no luck, but the chicken prices in general didn’t seem higher.

I wonder if it could be related to the difference between the way broiler versus layers are treated and kept. I think a broiler you usually kill after three months - they’re bred to get huge fast, and their bodies will literally fall apart if you allow them to live too long. (Volunteered for a while at a vegan rescue that took in chickens that fell off trucks, etc - they’d end up losing lots of feathers and looked terrible as they got older).

Layers I think are going to be kept in the conditions most conducive to spreading disease. You’re not killing them quickly, you’re trying to cram as many in a tiny space and keeping them alive as long as they’ll continue laying.

TL;DR: I suspect that we kill off the chickens we eat too fast for the disease to spread.