I agree, but I do think it's a common phenomenon in societies that pressure ppl to have children. That's why it's so precious that in modern times people are pushing back against the narrative that everyone has to have a family. Really, everyone is better off considering who they really are and if that much sacrifice will fit their actual abilities/resources/disposition/community. Like the parents messed up, but I get how esp in Korea, social pressure may have driven the inappropriate choice to have a child they couldn't really raise.
To be fair, the parents aren't people, they're a plot device shaped like people, but the people off whom they're modeled I can understand as above.

I can understand maybe 1 year of your child living with a relative due to unforeseable circumstances like illness or economic hardship… but the child’s whole life? Nu-uh, you fucked up bitch, what do you want a family for then? I know this is common in Asia, but what a horrible thing to do to your kids. It’s literally playing family. Also, since the grandma was that abusive, there’s no way the parent she brought to this world didn’t know she was abusive. What horrible parents.