They didn't need to actually show the construction of the barricades but it could have at least been more fortified as time went on.
The thinking and reasons behind this were discussed many pages back. Basically, the fortifications were fine for the amount of zombies that were showing up at the time. But then something changed, and something was luring more and more zombies to the fence/prison. By that time, more and more people were getting sick/out on missions. Not enough man power at the time to construct a fortress. Especially by using hand tools.
They could have been doing that long before the Woodbury crew came in and the virus. They knew the threat that the Governor posed. You would think they would have prepared better.
All in the past, I know.
Again, no reason to suspect more and more zombies would show up out of no where. In the end, any fortification they make to protect themselves against the zombies would have gone in vain because anything used to stop zombies is not going to stop a tank that still has live rounds.
I'm sure they didn't have alot of time to prepare things. Everyone was out doing other things to help the group survive. Finding food, ammo, gas, etc..
Right, I mean it's not like the last place they were comfortable in was overrun by metric crapload of zombies showing up out of nowhere. And it's not like they haven't established that the survivors have run into several large "herds" of zombies.
I mean, if there is one thing that the zombie apocalypse has taught us, it's that if you only see five zombies then you only need to prepare for five zombies because there will never ever be more of them.
Hey, if you're gonna compare a small wooden fence with a latch to a prison with two rows of chain link fence with survivors on the lookout at every second in guard towers, then thats what you gotta do I guess.
And as far as establishing some of them running into a "herd", that, along with the radio transmission was never relayed. And by then it was too late anyways.
The lack of defenses at the farm is irrelevant. The point was that the show has clearly established the exact opposite of what you claimed in bold. There was PLENTY of reason to suspect that more zombies would start showing up because more zombies showing up, and the idea of zombie herds that stick together, has been well established throughout the show (long before the episode with the radio transmission).
At Morgan's house in season 1, a large group of zombies suddenly showed up. At the quarry in season 1, a large group of zombies suddenly showed up. On the road in season 2, a large group of zombies suddenly showed up. At the farm in season 2, a large group of zombies suddenly showed up.
The notion that the characters had no reason to believe a large group of zombies would ever stumble upon the prison is absurd. It's a threat that they have constantly talked about and run into throughout the show.