Who decides when children are old enough to be alone: parents or social workers?

Who decides when children are old enough to be alone: parents or social workers? The 2015 Terrace BC ‘home alone’ case set the precedent that no child under 10 can be alone anywhere ever. It all started with a neighbour who works for Ministry of Child and Family Development getting angry at a mum over a parking issue. October 2015 Kids First media release includes letter by the mother BR to Premier describing what happened.