doctorbadwolf
Heretic of The Seventh Circle
Culture is commonly used much less broadly than you’re suggesting here.Sure, the Spartans were no less wise than the Athenians. They are, after all, part of Ancient Greece. Spartan Military might be a background.
Jocks and nerds are all from the same culture (mid century America?) so you would not give that culture a bonus to either group. Jock is a background. Nerd is a background
The New Yorker example makes me think your concept of culture is not mine. Those two groups you mention are part of the same culture. They are Americans. Culture is a broad umbrella. It's not the Yancy St gang versus the Fulton St. gang. High roller might be a background.
New York Punk Scene is a culture. Like...objectively, from an academic standpoint, or colloquially, it’s a culture.
American is frankly arguable whether there is a distinct American culture, or ever has been, even if we ignore than American more properly refers to people of the American continents, not just people from the US of A.