Are Piaget's stages really universal?

Piaget has said that he believes that concrete operations, such as understanding conservation of liquid don’t begin to develop until middle childhood. For the most part I agree with this theory. Chapter 12 discusses the role the child’s culture plays on their cognitive skills. It suggests that in non-Western areas some children may never grow out of the preoperational stage. As I kept reading it became clear to me that all children develop differently. The children in other cultures may not ever learn the conservation of liquid because their brains may not be developed in that area. This comes from inadequate education. Piaget says that his stages are universal, but sometimes this may not be true. I feel at some point, the children in non-Western communities can learn concrete operations if taught them. It just may not be at the same time a typical Western child learns them. The book also points out that children in other cultures have different life experience at different ages then we do. In non-Western countries it may be that a child has to go to work in the fields at a very young age. Or a child may be responsible for taking care of other younger children. When discussing Piaget’s “universal” stages, we definitely have to put a child’s culture into place. I do believe that all children will develop these cognitive skills at some point, even if it is in adolescence.