My chickens are kept sort of confined (they have an enclosed run, I can't free range here due to all the predators, and wanting to sleep at night) and I throw them some treats pretty much every day... just a few of course. Once they start to learn to eat the mealworms or strawberries or whatever table scraps they might get that day, they start to learn that I'm the Food Lady and they start to like coming up closer to me. Then I'll hold a mealworm or something through the wire of the pen, and some learn to come up and eat out of my hand. Not all, though... some birds are just naturally more wary. If they come up to me in the pen, I try and stroke the breast feathers with the back of my hand. If they can tolerate that, I can go from there.
You'd be surprised, I have taught some very wily old birds that came from another flock and wanted nothing to do with people, to come right up to me and eat out of my hands, even jumping up for treats and getting really comfortable. It takes a lot of time and patience.
It's not bad for them to be wary. I think it's a natural instinct that helps to keep them safe. But, they are not "bird brains" (LOL!) and they can learn.
