First question of the bank employee will be: have work permit ? (Wrong question) But as Tod explained, there is no reason not to open an account for a foreigner in THA.
Yes ! Visa O A or extension of stay comes with the permit to open bank (savings) account(s) in Thailand. What all the numerous bank employees are telling us since many years (Have work permit ?) is WRONG ! TiT !
... equal to and not less than ... MoFA A copy of bank statement showing a deposit of the amount equal to and not less than 800,000 Baht or an income certificate (an original copy) with a monthly income of not less than 65,000 Baht, or a deposit account plus a monthly income totalling not less than 800,000 Baht.