surely such areas are simply fed from appropriate taps on sub-station transformers? - there's no excuse for not providing decent voltages at both extremes.
Not always.
For us rural dwellers the power just normally comes out of the substations as a single 7200 volt feed and go for miles, some times 20 -30 miles, with a simple two conductor single phase or four conductor 3 phase overhead or underground line set out to the many homes and end users.
If the voltage drop is bad enough at the substation they will change taps to raise the output voltage there but still everyone is basically on what comes down to being just a really really long extension cord and how stable your line voltage is is directly proportional to where you are and how much load there is at any moment.
I for one am close to a new and rather large primary three phase feeder line that is double fed now from two substations so my voltage is generally quite stable regardless of how much power I draw even during occasional bursts into the 40+ KW range when my big shop equipment starts up while other high draw devices are running.
However if I tried running my same loads at a buddies place who is at the far end of a long single phase feed put in back in the 1950's there would probably be severe voltage dip issues large enough to affect numerous neighbors up to a few miles away from his place.