I was directed to Bangkok Bank at Phetchkasem Rd HuaHin. They gladly opened an account on tourist visa with the intention to apply for a long term 1 y visa aka retirement visa. I had to provide a certificate of residence from immigration which needed a rental contract and landlords id copy.
You can most times wing it without an IDP.. Thai Embassy guidelines say an IDP is law. Some people here dispute that. However Hertz and BizCar both required IDP from me sometimes when renting. It’s confirmed in their FAQs. Yes, Police sometimes won’t ask for IDP. However I was stopped when on a scooter in Jomtien at a tea money checkpoint and specifically asked for an IDP after I showed my EU licence….