American middle-class cultural hegemony doing its thing again.
Most Western-developed games do a hideous job of representing any kind of outlook or value set that isn't typical of the western, middle-class, white-collar demographic that create them. Even in settings far removed from our own, characters are uniformly coded with the same behaviour patterns that the average Californian aspires to. Living in dire, post-apocalyptic wastelands, heroes (regardless of their race or gender) are always more concerned with moral justice than where their next meal is coming from.
They all talk in complete sentences, rarely curse and almost never stoop to innuendo or lewdness. As such, you'll never catch them belching, farting, scratching their arses or picking their noses - despite being downcast, their sense of social propriety is impeccable (in fact, you'll only see these characteristics displayed in villains). They never speak about things like money either and seem completely immune to economic hardship, poverty or deprivation. Even when they're written as tribal outcasts, working-class outlaws, jobbing mercenaries or down-at-heel law enforcement agents, they'll rarely if ever say or do anything that wouldn't be said or done by the kinds of people who create these games. Imagine a post-apocalyptic protagonist, in a mature rated game, turning to a companion and saying, 'I must've eaten something off yesterday - I've been up since a quarter to six shitting my brains out. I swear to God, it smelt something had crawled up my arse and died'.
In the same way, protagonists will never be overtly religious or conservative either: post-apocalyptic settings almost always love a gruff, outdoorsy, working-class American (who in real-life count a huge number of committed Christians among them) and yet you'll never find a Bible in the apocalypse - you'll never catch characters praying or clinging to their crucifixes or asking god for help.
I'm just scratching the surface here, but there are dozens more examples, just inside America and countless more if you look abroad. If I create a tool to test the cultural diversity of most Western developed games along these lines, I think they'd fail miserably. And none of this is to imply the better representation across gender and racial divides is not important, but to pretend that this is only type of diversity worth pursuing is unreasonable and not a bit condescending.