in the case of the Aust Embassy, the Thais asked if they were going to guarantee the honesty of every declaration . Many? Maybe some? were abusing the system filling out false Stat Dec's, and the Embassy wasn't prepared to guarantee anything. So the thais said ok, we won't accept them from Aussies.
I use that method in Chiang Mai, and as far as I know, they really don't care where or how it comes from, so long as it has FTT (Foreign Transfer) on the bank statement.