Did no one realize Bon Temps was cut off from the rest of the universe? Like say for example the guy who delivers the beer to Merlotte's? Wouldn't he know something was up?
Maybe, maybe not. The whole season takes place in the span of, at most, two weeks, and the rest of the town being taken over didn't happen until the last 2-3 days.
There are rural towns which only get mail and other deliveries once or twice a week, and it may very well be that no one from outside noticed anything was going on while it was happening.
This is Bon Temps, an itty bitty town that wishes it was as big as Mayberry.