I was thinking about the “cartoonish” epithet that somebody tossed out somewhere upthread. While they meant it as an insult, it shouldn’t be. Stylistically there’s a fair point but it is intentional and purposeful. It is to mistake starkness for simplicity. The characters are drawn starkly. High contrast. The objective is to evaluate the differences between people, between worldviews, not to get distracted yet in the exact boundaries of where those differences are. Or... allow the context to become a character itself and too much a part of the story.
There’s a timelessness to the story and I think the style is there to support that. It’s “Film Noir”, to me anyway, as it plays in my head. I’m seeing cinema like an old Cagney or Bogart film. Sam Spade. I hadn’t thought about it before but yes, it’s even in black and white! Maybe a splash of color here and there... the blue on Rearden metal... some intense red on Dagny’s lipstick... the brief orange glow of a cigarette... but otherwise stark, dark and mostly colorless. Like a graphic novel. Like Bogart and Bacall.
Starkly drawn characters that don’t blend much with the setting, the decade, the techology at the time... it makes it possible then to tear them out of the story and put them down anywhere in time. The story is being told against this backdrop but it could easily be any other. Casablanca had stark, yes cartoonish characters, but it made for a story that wasn’t locked into a particular place and time but could find an analogue anywhere, in any time.
Where does your tag line come from?
By the way, "Casablanca" was set in that city during a specific period of World War II. But rent the 1984 film "Streets of Fire", and you'll see what you're talking about.