It's not like chickens chose this way of life. Such breeds were developed for the specific purpose of meat, with no regard for their wellbeing. Don't shame the chickens for what human bastards do.
Oh, sure, our fault, but fact remains that modern meat-chicken breeds are so incredibly fucked up that it’s not really possible to humanely farm them. They’re like that because of what we did, yes, but step one toward comprehensive humane-farming for chickens would have to be “let those breeds entirely die out” regardless of who’s at fault (and it ain’t the chickens).