I sure that was true , however in general the airport rate is usually well below what you can get out side so I personally wouldn’t advise anyone to change any more than essential maybe taxi ect at the airport
I don’t believe it would help asking in advance as I flew in from London yesterday via Thai air as I do regularly yet it is very rare that Thai air staff are on check in desk it usually or Canada or India or some other, I had 90 day return as usual but no visa never been asked