I think you mean "flighty." I don't believe that chickens or other domestic fowl are really that dumb. Consider their very short lifetimes and what knowledge they demonstrate after a few months?
Still, it can be a problem for those who do not cage. I don't do free range bc:
1) too many nighttime predators, including owls, one of which fell through the chicken wire roof into a previous enclosure and I found 2 hens dead
2) they would learn quickly to flutter up to my barn's loft at night and crap all over my horse's hay and straw!!!!
3) they would be up in the loft, thinking that they are safe and either one of my cats or a curious raccoon would have a meal
@ninnymary has the best setup for free range, which is a backyard with a fence!