I'm from the deep south. South Louisiana. Miles from the Gulf. I've lived in Texas as well.You simply don't see QR codes in Owensboro, Kentucky. And I'm sure much of the US especially the southern US see NFC as a useless gimmick overall. Without point of sale terminals to support it in anywhere other than large cities I don't see that changing. Just a waste of resources here.
You really only spot a newer phone from more wealthy folks and that's not common in a Mayberry style agricultural community like Owensboro. Regardless of the major hardware differences, the first thought to enter someone's mind when viewing the now - rare QR code is 'CueCat'. They are used to the similar looks since the codes once spammed their TV Guides. I remember when VCR Plus was a new thing, but no one even knew how to set the clock on the VCR so it ended up flopping. Can't see NFC being a game changer if the tech doesn't exist anywhere to make use of it. Like it or not, not everyone lives in huge sprawling cities.
The reason for the many iPhone 3GS in use today is either the hatred of iOS 7, or simply the feeling that 'if it ain't broke, don't fix it' mentality at work. If their iPhone 3GS works fine, gets signal and holds charge, why upgrade? They don't care one iota about retina screens or apps and the phone is just easy for them to use. They usually got one for email and such, maybe Weather Channel but that's it. Most still have a RAZR and to a lesser extent, a StarTAC. Most Android phones still run gingerbread. Same thing I suppose. Fits their needs and such. The 3GS is also super cheap and if someone wants to get into the Apple ecosystem, what better way to begin than with a $50 iPhone? Apple products do depreciate extremely fast, so people here take advantage of still usable if not a few generations old Apple products. Heck, I got a PowerBook G4 free, which still works.
Your generalizations are way off base. There are Galaxy S and iPhones everywhere. Their tastes in phones do not differ from anyone else. I haven't seen a 3GS on a long time when visiting there. Most people I know upgrade to newer phones yearly or every two years and they jumped on the iPhone 4, Droids, and Galaxy s4 when they were released even back in 2010. Their kids had iPhones. NFC I can't say. I don't even look for that anymore since it was such a failure to take off when Google pushed it and device support was/is so volatile.
QR Codes are a retro and most people don't use them. However, Google Goggles can read them, no?
BBM was using QR codes many years ago. A messaging app using that comes across as old school and retro. I don't know anyone who uses that personally.