Do you have evidence to back up that claim? I would imagine that only a minority of coops are actually founded by existing workers, and the majority would be new companies - certainly this is the experience I've had with worker coops near me. But it would be interesting if that wasn't the case.
EDIT: the France study is particularly interesting because they specifically talk about this as a potential reason for the surprising longevity, but then point out that "the overwhelming majority of cooperatives are created from scratch, and hence this explanation remains incomplete".
