Interesting. A few things:
As others (most recently dv8) have observed, the results are calculated in a way that's a bit nonsensical. The author is comparing the costs (we don't know if it's the average or median, which are two different things) of life in one U.S. city vs. dozens of countries.
As with everywhere else in the world, certain cities cost more than others. With the exception of San Francisco (and increasingly, DC) NYC is the most expensive municipality to live in in the country. Hardly a place where a retiree on a budget would look.
Likewise, the author compares, say, the entire nation of Brazil to life in NYC. Suffice to say, it's more expensive in Rio than in some exurb outside of some small city in the interior. Similarly, Casa de Campo may be a bit pricey, but it's unfair to compare Manhattan to Moca in terms of cost of living.
Anyway, DR long has seemed a pretty good deal for those looking to live on an island without feeling isolated by distance (like with Hawaii) or constricted by small as with New Providence Island/Nassau in the Bahamas. For example, my cleaning lady in ATL hits me for $100 per cleaning, which is quite a deal. Meantime, stories abound of 5x a week cleaning for a monthly cost of $200. The lawn guy is $100 a month for two visits. And private school can easily hit $25k, not including transportation and extracurriculars.
And, Atlanta is one of the more inexpensive big cities in the U.S. I imagine having 2k a month for a rental (which is about what you'd pay on a $350k mortgage) would get you something fairly nice. Further, nobody backs a fruit and veggie truck up to my house. And, I'm hours from anything resembling a beach or mountain range.
There are upsides and downsides. Yes, the power and water are issues, but not insurmountable (i.e., everyone on here has given advice on inverters and/or generators. I stay in Atlanta because I enjoy the culture of very much, and I love being in my home country. So at most, I'd probably just be a snowbird. But, done right, living in DR is certainly more than affordable.