From the age of 10, Amina has been scrubbing, sweeping and cooking in a middle-class home in Pakistan’s megacity of Karachi.Like millions of Pakistani children, she is a household helper, an illegal but common practice that brings grief to families often too poor to seek justice.“Alongside my mother, I cut vegetables, wash dishes, sweep the floor and mop. I hate working for this family,” said the 13-year-old, who leaves her slum neighbourhood in Karachi at 7am and often returns after...