Then they would not have qualified for the ED visa in the first place. So, what is your point? Someone had an _illegal_ visa and then gets denied an Elite Visa? Obviously. Someone has a valid ED visa and later wants an Elite Visa and can pay, he gets denied? UNLIKELY. Extremely unlikely.
I do not need to know the IATA rules. If you know them, why not post an excerpt? Fact is: if Thai Airways is flying you back from where ever you came from: they put you into a first class seat and charge you for it. Or did you answer to the wrong person and mixed something up?
It is not "by some airlines" it is by law. Big difference.
You are from Netherlands? I suggest to check what requirements a Thai has to fly there ... and then ask your self: why would the opposite around be different?
It is actually worse. What is more likely? The plane has an empty "economy class" seat, or an empty "first class seat"? I never heard that the airline is fined. It is technically definitely not the airlines responsibility to make sure you have a ticket. BUT: it is their responsibility yo fly you home. Anyway. The worse part above is: you budgeted a one way flight for peanuts, you get denied entry and get flown against your will back where you came from with a one way first class ticket. A one way first class ticket from BKK to GDG or FRA is about $5000 - $10,000. And the passenger has to pay that later ... the airline will confiscate your car, house or first born to get the money back :P
No idea what you mean with "no interest". The banks here pay interest. It is just not a lot. And with our days world wide low interest "season" you likely lose more money by an international transfer than you gain by having the money outside of Thailand.
"It is much easier to apply for the 90 days Non-Imm-O retirement visa in his home country, " in Germany it definitely is not easier. And for some odd reason" I assumed the "home country" process is everywhere the same?