NICE HAIR FOR STARS!!!!!!!! miley cyrus/ amanda bynes/ vanessa hudgens!!! help!?

Hi! i noticed that all the girls that are on t.v have really nice hair especially amanda bynes in what a girl wants… my question is since this girls surely have to get their hair done like everyday or so to shoot a scene why doesnt it get damaged?? Im sure the hair stylist uses flat irons and curling irons but why doesnt it damage at all and still remains looking nice??? while in real life others who straighten their hair everyday damage it and it becomes noticeable?????