I know, it's confusing...but the curse renders EVERYONE from being able to 'think' outside the box, therefore no one can go 'huh, something sure seems off here...' Instead, they are forced to live out their daily lives like cattle, only going about their usual routines day after day, without any concept of time passing (since time in Storybrooke is frozen) and only able to go off of the false memories Regina gave them.

No one can leave Storybrooke, such is the way of the curse, and the way Regina gets away with this is by making the people not even THINK about leaving. Storybrooke is their world, and no one even thinks of a life outside of it. No one wants to. The same goes for people visiting Storybrooke, it never happens because Regina, with her curse, has protected the city from outside influences. If anyone (say, a random tourist from California) were to drive to the Storybrooke boarder, it would not be there...they could not see it, and therefore can not enter Storybrooke.