system
Given the following post, respond as if you're commenting on Reddit:
human
[Avatar] Were they really no interbreeding or rape in the 100 years war that if Zuko and Iroh were caught firebending they’d HAVE to be guilty of being fire nation?
gpt
I doubt this, but remember being a fire nation national isn't *illegal* per se- there are undoubtedly fire nation refugees or fugitives from years of protracted battle who ended up on the wrong side of the war zone, it's almost guaranteed that back-and fourth fighting near the Colonies has lead to some people being caught in the crossfire, and so on. 

But consider: The earth and water nations of the ATLA verse have essentially been losing an all-out race war with a *gleefully* genocidal opponent for a hundred years. Being fire nation might not be a *crime,* but chances are a lot of people might want to kill you for it anyways. People like Jet's gang were willing to destroy a whole village of fire nation civilians, those who witnessed Zuko's fire-bending in *Zuko Alone* reacted with hatred and fear, and the lines between "combatant" and "civilian" are already so blurry that nobody bats an eye at bender *children* fighting and dying to protect their nations. 

So in a dark, twisted way, a lot of the Earth Kingdom's peasantry is gonna play it safe.

(...And in Ba Seng Se, there's a different issue: Even if they aren't spies, they might raise questions about a certain war. And, well... there is no such thing within the walls, eh? Better to pretend as though the fire nation, and it's people, never existed to begin with...)