Affordable in the U.S.?
I don't think so.
Consider someone on a 1300 SS check.
170 goes to Part B.
I'm seeing some small town backwaters with theoretical rents as low as 600.
Rents go up and most of such backwaters have almost no actual rentals
So maybe you could buy a basic house in such a place for 100k to 200k.
You could if you had that in cash. Nobody is getting a mortgage these days on that income.
No public transport in such places and little in nearby health care.
So you'd need a car to drive far for shopping and medical access.
If you could manage to get or keep a license as an elder, typical full running costs are 10k annually.
Yes you could do less with an old car but then that ups the repair bills.
Then there are the extra medical costs even on Medicare.
Typically several thousand annually.
Of course if the same person had 300k saved, more options in the US
Yes of course a working age person could bootstrap these days, work two or three jobs (not in a backwater with few jobs).
As said multiple times it depends on the specifics of the person's situation.