Hands up everyone who knows what a redneck is. Rather a lot of hands there, I see. Hooray for cultural imperialism (for those who are wondering, yes, that is sarcasm). How about an ocker? Yeah, that's what I thought, thanks Rowena and Chris. A bushie? Same two hands. Hmm... I think I see a little problem here.
I've got an interesting view from where I sit, because I'm not 'Merkin, but I live in the USA. It's very easy for 'Merkins to forget that not everyone has the same cultural references as 'Merkins. Yes, a lot of USian stuff gets exported, enough that most of the rest of the English speaking world has a fair idea of what the main US idioms actually mean.
It's not that the USA is necessarily more insular than anywhere else, either. It's just so flipping big that by the time you get through the USA stuff there's no room for the rest, kind of like the way it gets inside a large university.
Add to that the human norm is to assume you are normal and anything that isn't like you is not, and you've got a recipe for some serious confusion.
Say you want to write about the Australian equivalent of rednecks. No, I'm not asking why. I don't want to know. I'm just assuming it's something some crazy person might want to do at some point. You go do some research, and you find that lo! 'bushie' seems to fit the bill.
Only you're going to have the Aussies pissing themselves laughing at your masterwork, because you won't find a bushie with a truck up on blocks living in a trailer. He's in a tent, or a tin shed, or camping in the back of his ute, and he knows how to live off the bush. He likes beer, but that's normal.
Maybe ocker, then? They are kind of working class-ish, and tend to have that sort of feel... Except you get them everywhere. And there are some very wealthy ockers out there (Paul Hogan comes to mind. He made millions out of Crocodile Dundee by being himself. Hell he made himself plenty by being himself on the Naked Vicar Show (Yes, that was a real TV show, and yes, it was shown in Australia in prime time), himself being a smart-arse painter on the Sydney Harbour Bridge crew. The old footage if you ever find it, he's in grotty old shorts and a flannie shirt with the sleeves pulled out.). But wait! There's a catch. There's a bit of ocker in most Aussies, because ockers are usually also battlers. Oh, and ockers aren't inbred. Or dumb.
You go looking further, and come across the yobbo. This is a peculiar subspecies of ocker found mostly at sporting events, usually with six-pack (beer, not abs) and thongs (footwear, absolutely NOT underwear. If these guys wear undies - and quite a few don't, which leads to the unfortunates who get an eyeful of what's under the shorts developing a phobia of guys with beer guts and short short shorts - it's usually the jockstrap or Y front variety). Not right at all...
Which is the thing. The redneck is very much a USian phenomenon. Now the redback... Oh, never mind. You'll find out about that on your first visit to an old-style Oz dunny (outhouse, and yes, they're still around). Redbacks are spiders. They like nice dark, moist places and have no sense of smell. I think you get the idea. But I digress.
The point of this ramble is that every culture has its unique subgroups and stereotypes. You can write a redneck in anything US-based, and be fairly sure most of your readers will be know what you mean. There are others where that's not the case. Calling someone a liberal as an insult in the US has damn near the opposite meaning in Australia, where the Liberals are the conservative side of government.
So what are some of the groups you've seen dropped into books with the assumption that you'll know exactly what sort of person this is because he, she, or it is a 'redneck'? Or a 'yobbo'. Or a 'Tory'. Or... whatever.
p.s. For those who are wondering, you can get a start on some of the unexplained Aussieisms here.