Why would they need to? If they stay right where the are, somebody comes and feeds them every day. If they flew away, they'd more likely be killed and eaten in the wild. For a domesticated chicken, there's no survival advantage in being able to fly.
Man has been raising chickens since Adam and Eve and Alley Oop, and never kept them in cages until around 1960; the numbers which must have escaped in all that time have to be in the billions.
For all those escapees, being able to fly decently (as opposed to being to flap up into a tree with extreme effort once in a while) would be a gigantic advantage. It would let them escape predators better, and seek better conditions when necessary.
Again, the domestic chicken started out as a 1-lb jungle fowl and then got bred into a 7-lb meat bird with a 1-lb bird's wings. Geese are every bit as heavy as chickens and fly perfectly well because they have the wings for a 7 - 10-lb bird. If there was ANYTHING at all to Darwinism, somewhere in all those thousands of years and billions of escaped chickens, some few of them would have evolved the wing size they need to fly decently, and the progeny of those few would be overhead as you look up into the sky.
But in real life, it doesn't work that way. In real life, if you ever lose the tiniest bit of some complex trait, neither you nor any descendant of yours will ever see it again. Just like hair cutting: it's easy to cut off, and impossible to put back on.
Thus we see that the chicken lacks only the tiniest bit of the requirements for real flight and cannot evolve it, the question becomes:
How in hell can some dinosaur which doesn't have ANY of the things it would need to become a normal flying bird ever evolve ALL such things?
There isn't any answer to that. Face it: Evolution is a bunch of bullshit. It's a brain-dead ideological doctrine for idiots, and that's all it is and all it will ever be.