The average age of the large retirement community near me is 77.
But I'm sure they'd be happy to have you come in and volunteer some time with them. Who knows, maybe you can even glean some business advice from their experiences.
Local governments hate retirement villages b/c they are not net contributors to local tax coffers: they use up more police, fire, and medical services, they rarely purchase goods (IOW, no sales tax), and they don't own property (b/c the units are "leased" not owned) so they don't pay property taxes. On top of all that, they usually oppose new development in the vicinity of the retirement village, which can freeze commercial development.
The owners of the retirement villages pay property tax, just like every other owner. The local govts collect said tax whether or not said owners manage to get money from their tenants, so govts don't care either way about lease/rent/owner-occupied.
The age limits are two-fold - in terms of tax burdens, as one commentor stated, and also because it seems like lots of old folks want to retire where there aren't screaming bratty kids. Not all old people enjoy the dream of sitting on the porch and yelling "Get off my lawn!"
And many of those types are premium... and of course, often home to (or close to) medical facilities and other things old folks want to have nearby. Maybe they're cheaper than the cool parts of town, but certainly not cheaper than the normal suburbs where you have all-age neighbors.
It's surely not a social service.