See, did not originally see where you had said "life span" in the post. You have my most sincere apologies for mistaking what you had typed.
One thing should be said about Layers however.
For the first 12 weeks of their lives...they are housed in a poultry house and are allowed to roam freely within the house. Roosts are provided as well.
After 12 weeks, they are removed and a lighting schedule is done. So, in essence, they are not inside of the caging system for their entire lives.