My 7 children did no homework while they were in Primary school as I didn't allow it. I informed the school as each child approached compulsory school age.
As they went to the Grammars, that was a different situation and homework was given - sometimes 2 hours a night.
Further to this, there are many children whose home life is chaotic, neglectful, abusive and not conducive to learning. Bed and Breakfast situations, temporary accommodation, poverty. Expecting both children and parents to meet these requirements only exacerbates the already stressful conditions many families live under.