Question: I recently rescued a survivor from a portable toilet in *No Zombies Allowed*. Normally, this nets me some supplies, cash, and coins.

This one, however, awarded me by building a security fence all along my town. My first thought is that this does nothing but give my town a nicer look.

**Does this fence serve any real purpose?**

Answer: 
Surfing around google, I chanced across the [No Zombies Allowed Wiki](http://nozombiesallowed.wikia.com/wiki/Home).

I was looking for an answer to your question, and I chanced upon this in the [FAQ](http://nozombiesallowed.wikia.com/wiki/FAQ).

> 
> **How do I upgrade Lola's tower?**
> 
> 
> Every 5 or 6 survivors you rescue from the portable bathrooms, one of them will upgrade your tower and all
> your walls near your depots.
> 
> 
> 

Thus, the result is not merely a cosmetic upgrade, but also a defensive boost to your walls and fortifications.
You are correct in thinking that it just makes your town look nicer sadly. Would be nice if it had other features.