It's funny, we're so highly dependent on electricity for everything that there's not more failsafes in place. Generators aren't exactly super cheap, but they're at a price point where if your business requires power then having one in the wings is useful. Even more surprising that a big petrol station wouldn't have one.
It's also telling that when power goes down, or there's a big event (inclement weather and so on), there's a rash of panic buying, some incredibly ugly behaviour (looting, greedy price increases) but offset by some truly wonderful behaviour (free gas to stranded people? Friends for life at that stage). Society might be a veneer of polish, but at it's core there's still a lot of incredibly nice people.