solarpunk memes

but if you give people the opporturnity to do something that is convenient for them and fucks over others, far too many will do it.

That's called kleptomania, and it's actually pretty rare.

Normally, people are far too considerate of others and far too scared of even a slight possibility of losing someone's friendship or being marked as a thief to do things that fuck over others just because it is to their best judgment convenient for them.

Where it goes wrong is that people are placed in an artificial position where they are shielded from any such consequences. Where the best thieves hold the places of highest honor and wealth, where thieves have legal and physical protection if they steal the right way (including during scientific experiments, where the defectors are shielded from others through anonymity and the legal and social authority of the scientist), where people are forced to steal under contract under pain of homelessness. When there is no ethical consumption under capitalism, what more is defecting on the commons?

A mentally healthy person seeing the opportunity to screw someone over for personal gain warns that person that they've got a vulnerability so they can address it. They tell people when they drop their wallet. They look away from people typing their passwords. They give food to the hungry if they have enough to spare. They don't bother to lock their doors because to them locks are less binding than suggestions. Capitalism isn't the only force that get people to act like kleptomaniacs or xenophobes, but it is the first ideology that has managed to saturate the entire society with those modes of thought.

if you give people the opporturnity to do something that is convenient for them and fucks over others, far too many will do it. You need rules preventing that. The custom not allowing people to put more cows is that rule keeping things intact.

Exactly. And people, naturally, follow rules. Social rules, cultural rules, religious rules, how many people obey the law even when there is zero chance anyone will ever punish them for breaking the law? Humans are inherently hierarchical and tribal and have an instinct to obey authority.

That is to say, when there is a community, and there is a resource, that community will naturally produce rules to govern use of the resource, and people will naturally follow those rules. Coercion is rarely required. People will simply internalize, as children, that good people follow the rules.

Which is why the tragedy of the comments is something that occurs only in crisis situations. When people are desperate so they break the rules and take more than they need. When the people formally living there have been killed or driven off and the new settlers don't know what rules to follow to maintain the resource. And when people have been poisoned by a mind virus that valorizes selfishness and prioritizes individual profit above all else, so they believe it's right and moral to harm their neighbors for their own benefit.

Capitalist economists will tell you the tragedy of the commons occurs whenever and wherever resources are not privately owned. They lie. The tragedy of the commons occurs when capitalists are allowed to teach children that selfishness is a virtue.