Why are the shooting conditions of Hain dangerous?

The shooting conditions are very dangerous. In those years when filming child labor, Hein often disguised himself as a peddler selling bibles and cards, or disguised himself as an industrial photographer to "sneak into" the factory in order to avoid the interference of foreman and guards. When he really couldn't get into the factory, he waited outside the "sweatshop" where child labor was squeezed and filmed the scene of child labor entering and leaving the workplace.