In a libertarian society, there is no commons. From the roads you travel, to the restaurants, to the workplace, and so on, nearly every route, destination and trade would likely require a TOS agreement and some sort of liability coverage in order to participate.

My guess is that in most cases, that agreement and coverage for most places would be in place by virtue of membership to a defense agency belonging to a network, similar to the way that my ATM card works at banks belonging to any of the major bank networks.

Where a property owner or a potential customer want to do business, and either of them lack membership in a common network, the risk-averse person would likely insist on a special agreement for that particular transaction.

To my way of thinking, there is little possibility of interacting with people who aren’t subject to a consistent minimum code of conduct without knowingly forfeiting your own coverage during that interaction.