Pensions only began, as a right or entitlement, about 100 years ago if memory serves. So it's not exactly an ancient concept to give a fixed amount of money to the elderly. It is, to some extent, charity. I'm not sure I agree with the 50% figure, is that really true? My understanding was that the biggest share of the bill was housing benefit.
It is still a form of charity. And, even if it is not, a great many true charities in the UK do exclusively help those who live here. So Charity has "begun at home" in that sense instead.