Shared Systems
Cooperation that survives because defection is expensive.
Observation
Fungal networks move carbon and nutrients between trees, including between species. It is often described as generosity. Measured closely it looks more like exchange under leverage: the fungus controls the pipe and trades on terms.
Cooperation persists, but not because the participants are cooperative.
Pattern
Durable sharing arrangements tend to have three features: contributions are observable, the connection is worth more than a single defection, and there is a mechanism that makes withdrawal costly.
Where those are absent, sharing decays quickly regardless of stated norms.
Elsewhere
Maintainer economies in open source rhyme with this: visible commit history, reputational cost to abandonment, real value in continued access.
Irrigation commons studied by Ostrom show the same triple. So do internal platform teams, when they work.
Question
If observability plus cost-of-exit is what sustains sharing, could a struggling shared system be diagnosed by asking which of the three is missing rather than by appealing to culture?
Break
Trees cannot leave. Humans can, and can also lie about contribution in ways a nutrient flux cannot.
The mechanism transfers; the enforcement does not.
The resemblance is the beginning of the question, not the answer.