So, let me explain a bit.
What's going on here is, Michael was purposefully using informal speech towards the staff in a professional working environment.
Also, the staff was older than him.
And...
There's actually plenty of racist Korean, and since this timeline is when smartphone is not yet sold/invented, many people at that time is still not used to foreign or people who looks foreign.
Hence the bias that "foreigner is rude".
Those are times when American influences started to get into Korean, and they have American military base stationed at some areas.
Plenty of Korean-American youngun came back to Korea to start K-Idol career.
Because of that, their Korean language is not good, and nor familiar with the formal/informal speech.
So people just think they are rude.
These "foreign" idol did get discriminate too.
OHHHH so im just misunderstanding because of cultural differences, thanks for clarifying!!
Ok why are we making Michael have a baby as an opp (ALSO weird they keep painting foreigners really badly by saying some shit like “he thinks he can be rude bc he’s a foreigner” LIKE WHATTTT), I hate it when manhwa perpetuate stereotypes