Well, first of all it's not a geographical description. The nature of "hacking", which is a self-reliant activity of producing provisional solutions, has a lot in common with the ethos of life in remote areas or on a frontier. Even the word hacking evokes chopping firewood or doing some other woodwork task in a rough, ad-hoc way. This is combined with a sense of mutual aid which is often present even in (maybe especially in) thinly-populated areas. Gabriella Coleman might be a good source for more insight into this. Just why hacker communities behave as if they are isolated even in an urban environment is not something I understand, but from personal experience they are self-selected groups of people with particular traits, who often have difficulty being accepted by mainstream culture, or who scorn the mainstream.
I haven't read Coleman's book, but it is available here: http://gabriellacoleman.org/Coleman-Coding-Freedom.pdf
(When Dijkstra talked about "coding bums" in relation to APL, he didn't mean that they would be drinking and sleeping rough...)