The model I have seen is the family unit ( mom and dad ) have kids and those kids go out and have children without a partner. Then the grandparents are in a two income household and they provide shelter and income subsidy to the children. As far as that not mattering, it totally matters two parent households have many more options in terms of childcare and employment. The number of households where both parents have off hour jobs that are low paying is marginal at best. With two parents just by one parent staying home you can make almost as much as you would pay to have extended daycare for the kids.

So your numbers make sence. First generation Immigrants typically move as family units. They would also lack the social net to assist with kids, so they might be prime candidates for this kind of service.