Rosie the Riveter is a cultural icon of World War II, representing the women who worked in factories and shipyards during World War II, many of whom produced munitions and war supplies. Rosie the Riveter is used as a symbol of American feminism and women's economic advantage.
One reason factory owners employed children because they were significantly cheaper than hiring an adult. "the child is paired one shilling or one shilling and six pence". This shows that it's more cost efficient to hire a child.
Another reason factory owners employed children because of their size. Here is a quote to support this "The smallest child in the factories were scavengers they go under the machine". This shows that if the child is smaller they can do more dangerous jobs than an adult.
They kept the people together