Large demands of clothes require many people to work for many hours. There have been many occurrences throughout history of workers being forced to work in awful environments. A building was burned down while women inside died because of a locked door that forced them to work: Tringe Shirtwaist Fire in 1911. A building collapsed that injured and killed workers because of "extremely poor quality" materials even though the owner was warned, possible money couldn't be wasted: Rana Plaza 2013. These are bigger events that could be said to have been a mistake and rectified but there are still many other causes that harm workers, like spraying pesticide to cotton farms that can cause cancer to people. (incomplete)
Image taken from this website.
Image taken from this website.