They're pretty skittish by nature. Trying to handle them stresses them out, and stressed chooks don't lay very many eggs. They do build up bonds with people and can be handled by those they trust, but this can take several months and will try your patience. I'm currently trying to build trust with a mob of kangaroos, who are even more skittish than the chooks. For that, you've really got to be in it for the long game.