Why was Toph put in a wooden cell in the Fire Nation city in Season 3 Episode 7?

Question

It doesn't make any sense that Toph is put in a wooden cell. Reasons -

1. It's a Fire Nation town, where the chances that the authorities would round up a Firebender are high, and the Firebender can simply burn their way out of prison.
2. Toph didn't reveal in any way that she was an Earthbender, and that too, a Metalbender, a hitherto unknown art which she invented. The then-situation between the Fire Nation and the rest of the world would imply that even if they catch an Earthbender right in the middle of the Fire Nation (the town is Fire Fountain City, a town located on the main Fire Nation islands), they'd send them to higher officials, possibly to the Fire Nation Capital.

Are there any reasons as to which her being put in a wooden cell makes sense?

Answer 1

Are there any reasons as to which her being put in a wooden cell makes sense?

The simplest and best explanation is that they knew she was an earthbender. There are two ways they might have known:

1. Her "wanted" poster was for "The Runaway". Who did she run from? Her parents in the Earth Kingdom. I don't think we have a direct translation of the wanted poster, but it's likely she was described as an earthbender or simply as an earth nation child, and therefore not a firebender.

2. Upon her capture, we find that the actual imprisonment is orchestrated by Combustion Man, who was hired by Zuko to kill the Avatar. We presume that Zuko would have briefed Combustion Man on Aang's companions, so he would have had full knowledge of Toph's capabilities.

The dialogue suggests strongly that #2 was true:

Toph: (alarmed) Hey, what kind of cell is this?

Female Fire Nation Officer: (through the bars) A wooden one.

Cut to the mayor's office. The mayor is opening a moneybox for Katara when the door creaks open. The mayor points to Katara and speaks to a person in the doorway.)

Mayor: That's her. That's the girl you were looking for.

(Katara turns around to see the hulking figure of Combustion Man looming over her.... Katara has joined Toph in her cell.)

Toph: Wait. It's a trap!

Katara: Really? No kidding. Is that why we're sitting in a wooden cage right now? Gee, how'd you figure out it was a trap?