Someone who knows the Korea culture well, please explain me this

[pedrohemg 7,802]

So, I was watching a video of two actors of the series All of Us Are Dead. In two moments, the boy seems kinda worried about the way they speak to each other. I don't quite understand his reactions.

At 2:19 he says: "By the way, I feel awkward when we suddenly speak in honorifics".

At 8:31, he's kinda shocked by the sudden casual speaking. At least, this is what the subtitle says.

 

[RAMROD 96,461]

(East) Asians societal structure is vertical, where younger or junior need to be respectful of older people or their senior (ie in school or workplace even if they're younger), regular citizens to politicians, men to women, women to men, and poor people to richer folks, so there are certain way people talk to another people based on that.  There are certain words you will not use except to people you are very close with because it is too casual and impolite. Even they way they greet other people got rules in it. Either how low you should bow, or how high your hand must be when doing the Wais if you are Thais. 
 

Most of them are growing up taught and conditioned to this system. Even the ones who immigrated abroad like Asian Americans would still heed this when they are talking with fellow Asians. Even me, who is a half Asian, was taught these stuffs aside from lots other Asians stuffs by my late mother since I was young. Though some may flipped 180 in attitude and be more casual with non Asians and be their genuine self more. 

[pedrohemg 7,802]

9 minutes ago, RAMROD said:

(East) Asians societal structure is vertical, where younger or junior need to be respectful of older people or their senior (ie in school or workplace even if they're younger), regular citizens to politicians, men to women, women to men, and poor people to richer folks, so there are certain way people talk to another people based on that.  There are certain words you will not use except to people you are very close with because it is too casual and impolite. Even they way they greet other people got rules in it. Either how low you should bow, or how high your hand must be when doing the Wais if you are Thais. 
 

Most of them are growing up taught and conditioned to this system. Even the ones who immigrated abroad like Asian Americans would still heed this when they are talking with fellow Asians. Even me, who is a half Asian, was taught these stuffs aside from lots other Asians stuffs by my late mother since I was young. Though some may flipped 180 in attitude and be more casual with non Asians and be their genuine self more. 

Thanks for the explanation. This makes sense, but I believe not all of them cares too much as that boy. Since the first video I saw of him and other cast members, I noticed he's too polite, while his friends are more chill.

[Lukasson 407]

Glad to be living in Berlin where I can call anyone an a**hole. Even if they’re richer or older than Me.