I was just always mad that, while they were at the prison, they never dug a moat. Or a big ditch. Build a drawbridge or something for human use. Then every night, set fire to the zombies in the moat and roast marshmallows. Then they wouldn't have had the fence problem.
Then again, on Lost, I spent the first three seasons being angry that no one had yet circumnavigated the island. What if there was a luxury resort on the other side of the island? They never would have known!