I still think there is significant OPTIONALITY over costs in Thailand.
On one day earlier this month, in Isan, I took a train, stayed in a clean brand new hotel,, had 3 coffee shop visits, 2 fine meals, some snacks, other expenses and a fit young lad shared my bed for a a while. Everything I wanted in a day and the total was just under 1150 baht.
That is as a tourist, without trying to scrimp.
OK, so I got lucky with a rare example of a fit lad who didn't want money. Plus there isn't that much to fritter money away on in some towns.
On another day, I spent almost 6000 baht, including almost 3500 to get s boy from a BKK gogo bar & tip him.
The choice is there. Anyone who decides to live in a less expensive part of the country and adapt their eating and other expenditure towards local styles could probably live very cheaply.
However, the expat cost of living indices will be based on near prime Bangkok, not some town in Issan.