Distance is a factor. I do not know what they were measuring (the main power plant was about 1000km away, but I don't know if they counted that or if that was ignored because someone else owned those lines). They were a fairly rural utility with most of the area belonging to farmers (but they do have a couple suburbs and a few small towns).

I don't know the real details, but my educated guess is they raised the voltage, and also they used 3x as many wires (running 3 phase past every house even though almost everybody only used 1 phase). That is I can visually see their insulators on the power posts are larger than neighboring utilities which allows for higher voltage (but may or may not mean higher voltages were used). Likewise I can see the 3 lines on each power pole while neighboring utilities only used one. It is hard to tell from the ground but I suspect they used thicker wires as well.