> the "natural" way of things is older generation gets supported by children and they help take care of grandchildre

It's an ideal. Structuring society to require it falls down often because:

- people have kids later, making them too old to help

- disease and addiction can make grandparents unfit

- young families often must move to where work is, even if far away

- deeply in debted grandparents may be unable to afford to help

- grandparent's own care needs compete with those of their grandchildren, i.e. sandwich situations

- cultural expectations unfairly burden some over others, usually women