Wills can be so specific or vague I'm sure banks would not want to get involved in trying to do the court's job in reviewing a will (or lack of will) and being up to date on all the related inheritance laws.

And I'm sure the Administrator, which can either be appointed within the will by the person passing or by the court, is limited by law in many aspects in the distribution of assets...probably still needs the court's approval on Administrator recommendations for distribution of estate assets. I think these two Links give some insight on Administrator duties, who can appoint them, their interface with heirs, succession under Thai inheritance laws, etc.

http://www.samuiforsale.com/law-texts/law-text-administration-inheritance-law.html

http://www.thailandlawonline.com/thai-family-and-marriage-law/legal-aspects-of-a-last-will-and-testament-in-thailand

Actually, not much different than in the States: Testator dies, leaving a bank account singly owned, with no Pay on Death beneficiary, so the executor (or administrator, if court appointed) has to get Letters of Authority from the probate court. This is presented to the bank, along with a death certificate, and the bank checks Ltrs of Authority to make sure the name on them matches that of the account holder. Account closed, money transfered to the executor. The bank doesn't care what happens next, as it's the executor's fiduciary responsibility to make sure the money ends up with the Will's designated beneficiary(ies). So, no need for the bank to see the Will. Executor's a crook? Maybe, that's why some Wills require bonding (although, that's pretty much a slap to your chosen executor, so most Wills include "to serve without bond.")

But, based on Bangkok Bank's requirement for paperwork from the probate court, it's beginning to get clearer that all valid Wills in Thailand (holographic, lawyer drawn-up Wills, and Amphur (registered) Wills) need to be probated. You may find a Bangkok Bank manager who will accept your Amphur Will without probate. But, this doesn't sound like the kosher guidance from Bangkok Bank management on high.... Oh well. She won't need my bank account money in a timely fashion anyway.