Edit: the toilet thing is what I've seen for transport in open-trucks. For most of their lives they're just crammed horizontally.
Rows of adjacent cages keeping groups of chickens in close proximity with each other with shared air.
I'm not advocating for one or the other, just explaining. Even cage free chickens will come into close enough proximity where they will all die if just one chicken picks up the flu. It's incredibly virulent.
Are they getting bird flu at a higher frequency?
This is from Australia, but whatever:
"In Australia, indoor and free-range poultry, are at risk of contracting avian influenza due direct and indirect contact with waterfowl who may carry avian influenza virus in their nasal and eye discharge or faeces, farming and biosecurity practices.
Indoor (barn or shed) systems limit poultry from direct exposure to wild birds, but these are not immune to avian influenza risks due to indirect contact. This is because equipment, vehicles and human movements between farms can introduce the virus indoors, in particular when on-farm dams or open water sources act as a permanent residence for waterfowl.
Birds with outdoor access (free range) are at risk of coming into direct or indirect contact with wild waterfowl. Vegetated range areas may attract waterfowl, in particular if poultry are given feed or water outdoors. In free-range production systems, producers should therefore focus on managing these systems to reduce the risk of avian influenza."
https://kb.rspca.org.au/knowledge-base/what-is-the-risk-of-f...
Granted, I don't know much about chickens, but a lot of this is common sense. I'm not sure what you think I'm wrong about.
For the same reason that the main guidance during COVID was "be outside if with other people" and not "stay inside if with other people".
Thus stuff is not related, wild to see people trying to conflate it.