My Little Sister's Farm :
3 reasons they are hard to find:
1) Companies don't want you to know what condition their birds are in when they are done with them.
2) They don't like to provide their genetics to the public. Their genes are the biggest value of their company if they breed their own.
3) They are euthanize when they are done with them.
I wouldn't suggest adopting these hens if you need them to be calm and well adjusted when they are in your backyard. They have been in a cage their entire life and are scarred. They don't necessarily adapt and become good outdoor birds and they especially don't calm down. They are flightly and would need a gentle hand and someone who has time to give them space. I would suggest having a large cage to start them out in if you do end up getting them. You need to start out slowly. Throwing them in with the other birds (even after a quarantine) could end up stressing the bird out and ruin any progress you made.
our three rescued girls are lovely, happy, and took to being outdoors immediately. And luckily, they'd grown all their feathers back by autumn
maybe we were lucky, but they just loved being able to move around and dig and all the normal chicken behaviours, and started within an hour of being let into their new home