We said we would answer your questions, and this was one of them. So here we go:
We had to do some research as to why chickens can't fly, but an article from LiveScience.com gave us the answer!
If you've ever been around chickens before, you might have noticed they have small wings. But what's even more interesting is chickens actually have the muscles to fly. Unfortunately, they've got TOO MUCH muscle. The article we linked above states, "their muscles are too large and heavy, making it hard for them to take off."
It might sound counterintuitive, but the chicken's large flight muscles impede its flight. In order to fly, birds need appropriate "wing loading" — a ratio of body mass to wing area. Birds need to have at least 1 square inch of wing per 0.6 ounces of body mass (1 square centimeter per 2.5 grams) to fly.
If you've ever been around a farm, you might have noticed that a chicken might be able to "flutter" a few feet in the air but that's it.
Looking at it from the angle of intelligent design (meaning that God created ALL things), I think it's fair to suggest that perhaps he designed them that way so they'd be easier to catch for food.
Simple math here shows us that because they're easier to catch for food, it's far easier for Chick-Fil-A to stock their supplies and feed us that good food. That's just speculation, but we DO believe God is intentional so that may be the case.