A question for hunters and their attire?

Why is it that camouflage is the unofficial color of hunting? You see all these guys (even when it's not hunting season) wearing all this camo gear as if they are all tactical? I've even seen guys who cover their entire truck in that plastic camo stuff. Is all this really necessary? My grandpa talked about growing up in the depression and how they HAD to hunt for food. They wore whatever they had to wear and still made kills. Remember Elmer Fudd? He didn't wear camo. Why is hunting today require camo when in years past it never did. Maybe a big heavy coat would be worn.