Over time, the family unit provided the primary support for older people. This is still true for informal support. The advent of Social Security, however, changed the status of formal support. Economic support for the elderly has gradually shifted to societal exchange. This income transfer from workers to non-workers is moderated through government outside of the household.
Most older people prefer it that way.
They don't want money to interfere with the bonds of affection that provide psychological and social support. Colonial times featured an agrarian-based society. The old people owned the land. By holding onto land ownership, the older people could expect to receive help. Thus, the parental generation helped establish the one that followed.