I think the real point of miscommunication between us is your concept of efficiency. Literally everything about our modern, western life is unsustainable, no matter where you live. Urban places are less inefficient, but they're still monstrously unsustainable. In the United States, even if you stop traveling, heating your home, and barely even eat, you still live unsustainably due to the government that operates a military on your behalf.

To actually live sustainably, we have to fundamentally reimagine society. I don't think it's at all obvious that this new society's rural communities need be unsustainable. In fact, I do think, as I said elsewhere, that any sustinable world is going to necessarily have more rural inhabitants, because the agricultural workforce will probably have to expand a lot, and probably be significantly collectivized, if we want to fix our food system.