This seems to be the trend now in Pattaya. The answer to your question is yes you can open a bank account on a 30 day visa on arrival but you have to go to your local immigration office and ask for a residency letter. This is a document with your photograph on and your current address stamped by the immigration bureau. When you have the residency certificate you can go to most banks and open a bank account. When you go to the immigration bureau you need two passport sized photographs and something confirming your address in Thailand i.e. rental agreement, hotel receipt, or home ownership information. The residency letter issued by the immigration bureau can be used for purchasing a motor vehicle or motorbike in your own name, obtaining a Thailand driving license or opening a new bank account.