I'm an English teacher and I think kids don't actually need homework, so much as teachers need more time in the classroom that they're just not going to get. Homework is the spillover practice tasks that we don't have time to have students do in class, because we have to get through a certain amount of material in a class of 30+ students, who all have different learning speeds. If I was working with just one student, he would never have to do homework. But because we can't put our full energies into just one student, but must instead parse it out among so many, homework time is supposed to compensate by giving students time to think and process the material further.