It's indeed unsurprising that if you look at the designs produced to match a specific context (AirBnB) you'll get a good amount of uniformity, as sellers converge on efficient solutions. If you looked in other contexts (high end apartments for sale in major city, cheap new builds in small towns, mass produced single family homes in another country) you might end up finding more differences.
I would probably look at listings of new apartments in various parts of the world to get picture what is common and what is not. And this should be matched to similar segments(low, mid and high income) in each location.
And even that is fraught with problems, because in my neck of the woods (Germany) we generally do not buy houses/appartments furnished (and renting appartments furnished is also an exception and not the norm. Even kitchens are empty rooms without cabinets and appliances.).
Edit: Even though the AirB'n'B methodology is not perfect, I agree with some of the conclusions. Just like radio/tv has smoothed out local accents and dialects within a country, the internet produces global trends. This is not all bad.
That is bassically the same here (usa), although we typically include major appliances and cabinets.
However, when houses are put up for sale, they are typically "staged", where the seller will rent furnishings to make it look more homely.
Apartments are more hit and miss. The bigger complexes will often have a show apartment they keep furnished for toors, and may often used a furnished one for their pictures.
Obviously the way you furnish a house for show is not the same way you would to live in it. But it seems like a reasonable approximation of the 'average' sensabilities of the market.
Nobody can afford to furnish an apartment the way big complexes stage their model. They rent good-looking but useless furniture from some place like Rent-a-Center. They can afford the rent on it (they pay for it pre-tax, while actual people have to pay for it post-tax) but its such shoddy quality that it will fall apart as soon as you use it. I've never seen anyone decorate their apartment like this. Even AirBnB hosts quickly find out that they can plaster cheap glittery decorative tchotchkes everywhere but the bed and couch need to be something that won't fall apart if you look at it wrong.
That would definitely be better, although you're still only capturing part of what's available, or at least a biased sample of what's available. Different form factors come onto the market at different rates - some may never be on the market, or not in an easily accessible manner (sold locally, or via word of mouth, or via private auction etc). I think perhaps that's a distinction that the article fails to make, it's easier than ever to access goods and services from all over the world, but that ease also favours mass market products. If you put as much effort into doing whatever you're trying to do as someone would have pre-internet, you probably have access to at least as much variety as they did.
