Putting aside most of the exchange above, THAI used to have 'limited access' fares available only to people meeting particular requirements (which were not publicised).
The specific example I know about (from 20 years ago, and may not now exist) was a fare sold in NZ (and probably other markets) for overseas Thais at significantly reduced rates to those being marketed by travel agents (no/limited internet in those days).
My wife (who is Thai) heard about this from the Auckland Thai community, and so I enquired with Thai if such a fare was available or not. The fare did exist, but my memory fades on the requirements and applicability. I think a Thai passport was the main requirement. I also think that non-Thai partners could access the fare if proof of marriage was provided and the travel dates were the same.
My assumption at the time was it was a (govt-directed?) means to encourage Thais living overseas to visit/return home, perhaps to bring skills/investment back to Thailand. I wonder if Philippine Airlines has anything similar for the massive numbers of OFWs?