Came across many articles while searching internet. it seems like in western countries it has been discussed/practiced much more than our part of world, may be due to the fact that not many women are working here, and joint family system so mostly there is always someone guarding a kid. Large number of women do work in agriculture sector as labor in non-mountainous areas, in mountainous areas, i saw many women managing their own farms and growing own food and fodder for animals. so quite possible parents of children in picture are just working in their farm while kids are hanging out in neighborhood.