
Well the teach indeed experienced the savage world, like he was saved from being murdered in his old house, he was very surprised about how this group managed to stay nice, quiet, civilized. This wasn't presented to him
Now, that rule isn't very well funded nor functional. They all knew the reason why he stole, a more functional and useful way of punishment for breaking a rule like that rule would have been going to get more medicine with the exploration group, and if he tries to run away or doesn't give any results in a determined time then
The way of how that rule is imposed will end up making a witch's haunting. If you don't agree with someone, or you don't like them you could say to everyone that they've broken a rule and plant false proof to incriminate them. It's not really good. They are all moved by emotions, not rationality and if that keeps going, they all firmed their death sentence

get behind me omg... everyone's applying morals to a post-apocalyptic world I dislike Guwon choosing a slow death method instead of a quick one, but I agree with you that Jinwoo's probably gonna be the typical, annoying "I won't kill anyone cause it's wrong" virtuous character
I don't completely agree with Guwon, but it was already implied in the beginning that it took a lot of work for them to build and secure the town cause of the disorder and chaos that followed after the world got destroyed. someone has to dirty their hands or else no one's gonna follow the rules.
does this make the town a good place? no, but this is a post-apocalyptic world and they're just trying to survive
Teach has the luxury of maintaining his humanity because he hasn’t experienced the horrors of this new world (at least he can’t remember experiencing them)
I’m with Guwon. Can’t let him go, because if he makes it, he could tell others where their town is. I can already feel how much Teach is gonna annoy me next chapter…