Well, you call those "voluntary" but how is that going to work in practice? Being/wanting to take new members into the community is at odds with people knowing

Well, you call those "voluntary" but how is that going to work in practice? Being/wanting to take new members into the community is at odds with people knowing each other well (and being able to rely on one another). If people can voluntarily enter/exit any region/community they want, what prevents criminals to just leave without justice? And if not, it goes against the idea of being voluntary member of the community. I think there needs to be some balance of these two opposing forces. At minimum, I would love to see these anarchist ideas backed up by some computer model.