it's true. Some Thai got message to proof manythings at bank and still do not pass. Even though their account are not mule account and amount is equivalent to 40,000 THB. It's operated by Anti Money Laundering Department.
Yeah. I saw a lot of Thai people got their account blocked by bank and must provide proof of income. They can't open any new bank also as their ID is shared among other bank.
I think it would be now way harder for foreigner to get bank of short stay visa.
Something must be wrong. Because no way TM .30 can be provided before you stay at a place in Thailand.
You may request your employer to write in Thai state the place you are going to stay in Thailand and it is impossible to request tm 30 when you are not staying in accommodation yet.
Any activity that make you earn money in Thailand require work permit. After some transaction abroad. Your income transaction will be blocked by bank and must be declared at bank using related documents. And that also includes paperwork to prove that your business is legally opened in Thailand and you are legal worker.