Yes the industrial grade "food" the chickens are fed, because of patent laws or outright corporate litigation I don't think the farming industry has had to tell consumers the complete truth.. and when it comes to food this is importantYou mean the food the chickens are fed right? Although I'm still skeptic towards your last sentence.
Also in my experience the inner membrane toughness is not really correlated to free-range or not.
At home we have 2 chickens and sometimes the membrane is tough sometimes it isn't.
The same with store bought eggs, depends on the batch.