I always feel the Air Force looks down upon close air support in favor of their more strategic mission. But they would never let the Army take CAS from them.
In case my opinion isn't obvious, Everyone else has planes, why not the Army too?
Nah the Navy and the Marines are both under the Department of the Navy, but they do way different things. Marines mostly get rides from the Navy and the Navy don't fuck with land, they let the crayon eaters do that.