I'm currently working as an expat, and my grandparents used to work overseas but retired to Canada so you could say my family has done things completely the opposite of what you suggest.
However there are a number of very good reasons that my grandparents have done things the way we have, and I think it's worth sharing the rationale there.
Low-cost moving to high-cost is a no-brainer: it's not easy to do, but many people are trying nonetheless. However, even they will be likely to stay in the high-cost countries, mostly because of health care, also safety is a factor, but social factors also matter.
Firstly, I think two key factors that have been overlooked are language and health care-- most low-cost countries speak different languages than high-cost countries.
Language & Culture
This isn't a problem if you're young, but it becomes prohibitive if you are older. Even if you can manage, it's inconvenient in most countries. You can't just walk down the street and do whatever you like. You either have to keep a translator handy, or restrict your activities to places where you can communicate in your native language. Your favorite sports channels (rugby, american football etc.) might not be available, because nobody there cares. Your favorite news channel, or food (even in grocery stores) might not be so readily available. All these reasons made living abroad undesirable for my grandparents, but the big deal for them was healthcare.
Outside of the US, every single developed economy has socialized healthcare to a large extent. When you're young it doesn't really matter, but when you are older, it's a constant concern! There are two aspects to healthcare-- firstly, if you are a citizen in a developed country there are significant financial benefits (In the US there is also medicare/medicaid but I don't know how those work so I'm not going to talk about that) to staying in-country when you retire, even if the health care would be more expensive- it's the government that's paying! Secondly, health care in low-cost countries tends to either be cheap and poor quality (and by poor quality I mean really, really scary!) or expensive and almost as good as a developed country. Again, high-quality hospitals in low-cost countries may still save you money, but the nurses may not speak good English and the doctors may not have a great bed-side manner.
In many low-cost countries, nobody calls the police because they know the cops don't care, or will never solve the problem (i.e. they will arrive hours or days after it's too late), or the cops may even be 'in on it'. So basically you try to protect yourself from the inevitable robbery,swindle,extortion,hold-up,you-name-it but sooner or later something bad will happen. With security guards and being younger, it's less of an issue, but when you're elderly, especially if you look foreign and rich, it's definitely more dangerous. Many of my friends from low-income countries try to emigrate for this reason (and/or in combination with the political climate, which is largely corrupt and full of problems). So, if you're old, why risk it? Stay somewhere safe.