

Selective: there is either a process which rejects a nontrivial number of applicants (in a way which is not random; the output distribution is different from the applicant population), or there is no open system to join the commune at all (and the initial members are again very much not typical).
Long-standing: a continuous group has existed with the same name for more than, let’s say, 25 years. Ideally in a similar place and with similar policies, but I’m flexible.
Commune/community: a democratically run sharing of resources and container of social connections. They must have things held in common, to which any productive member contributes and any needy member can draw from. The things must be controlled according to the groups intent. Participation in this process should be high. A significant portion of social life of most members should stay within the community.
Successful: a vibe, but not killing too many members and improving the quality of life for members seem like good minimums.
Definitions are meant to be broad here, because I would like to hear about your oranges. Close examples that miss:
Most governments (not communal or not democratic)
Most churches (quite selective, required beliefs for example)





I agree that the bar seems to have raised; the implicit assumptions were taken from the OPs quotes. That was the intended context, apologies if that was not clear.
Non-selective bodies: food banks that serve all who appear, common greens and parks, public libraries, perhaps some gyms or cellular networks. There were a few intentional communities that took a broad welcoming stance, I think New Harmony Owenites is one I’ve heard about.