It appears that if you use your Thai bank card in a different Thai bank's ATM machine then you are allowed to do it 4 times a month with that card for no charge, the 20 baht fee has been dropped for 4 times a month.
I went to a Bangkok Bank ATM and used a Kasikorn card in it today and the message came up on the screen that I wouldn't be charged for 4 times I used this card at BBK Bank ATMs to withdraw, also later used a Krung Thai card in BBK Bank ATM and said the same.
Haven't tried another bank's ATM yet, but definitely the case with BBK Bank ATMs.
Worth letting folks know though, even if it's just small change.
