I see where you're coming from, but you emphasize a widely held stereotype about the 'american prepper' which I think A. isn't true, and B. makes it seem almost fatalistic, which is the idea of "every family for himself".
I think in reality what you have in the rural US are communities that are ready to band together in hard times.
Perhaps a more clear way to think about the situation is in terms of distributed computing and graph theory. As many of you know, in theoretical computer science, the CAP theorem states that it is impossible for a distributed computer system to simultaneously provide all three of the following guarantees:
Consistency (all nodes see the same data at the same time)
Availability (a guarantee that every request receives a response about whether it succeeded or failed)
Partition tolerance (the system continues to operate despite arbitrary partitioning due to network failures)
I think that some individuals in the United States (the ones who live in large metros) prefer to optimize for Consistency and Availability by living in populous areas. There are more firefighters, paramedics, and power company linemen ready to step up quickly to restore services in the event of an emergency.
People who live in rural areas in the United States are optimizing for Partition tolerance, but that doesn't mean they expect to one day become completely independent nodes (that's merely a stereotype), instead they anticipate that eventually a few vertexes up the graph there may be some unexpected latency, or even a network partition.
The prepping culture can be thought of a distributed systems protocol which enables "self healing" characteristics so that a temporarily cut off part of the cluster can avoid downtime just by shedding a little consistency. (Guns help them reject corrupted messages from outside of their sub-graph during a partition, it's a form of security isolation)
One could argue that large metros also have this capability just that their RAFT leader election process takes longer (gangs shooting it out) whereas rural communities have an easier time with it because there's less chatter on the network. Prepper communities have more caching, and they store more shards on every node. ;)
In Europe they have more of a monolithic architecture from what I gather although they've enjoyed pretty decent uptime.