As far as I could tell in the movie the rich people were depicted as decent parents if not a bit naive, while the poor family were backstabbing assholes who betrayed their fellow workers (the housekeeper and her husband) because of sheer malice. Not once does the film hint at the underlying economical system as the reason why the rich are rich and the poor are poor.
If you are a socialist, you will (correctly) identify capitalism as the reason for the misery of the poor people in the film, and the rich as part of the bourgeoisie who exploit them. But that isn't any different than analysing an IRL crime through that lens, the film didn't help you reach that conclusion, it just presented a scenario.
A chud could easily see the rich family as the honest entrepreneurs and the poor family as poor because of the negative behaviors they exhibited, and there is nothing in the film that would dispute that interpretation.
With the poor family getting punished for their deception, and the son resolving to make money to save his father at the end (presumably through more "honest" means), it even displays the "pull yourself by the bootstraps" belief.
The best case interpretation of the film I can make is that "the rich people should be more conscious of the poor's struggles, and the poors should stay in their place or risk losing everything" which is pretty reactionary and not the class conscious film many people described it as. I guess you could see the ending as punishment for the class betrayal but I think that's a stretch.
Am I overzealous in policing the politics of the media I consume to the point of misinterpreting things or finding an even vaguely leftist film that hard?
That was said by his mother who was already shown to go to the worst case scenario, like the scene where her son's art gets evaluated. The son wasn't in any danger as it was a psychological response and not a life threatening condition. The mom might've believed there was legit danger, but in the context of the movie, the son would've been fine.
Yeah my bad, I often miss such behavior details
I think that's by design actually. As the viewer, we're led to believe the wealthy person who treats their problem like an emergency. It's only through paying attention to the details that you can see how minor their problems are.
They were both affected by rain for example. The wealthy family complained a lot more about day camp being cancelled than the family who had to deal with flooding and displacement.
Parasite really highlights how the wealthy get sympathy by default.