Banks in Thailand are like everywhere in the world, interested in having good stable customers, that have a permanent address, a steady easy traceable income, and use the account all year round.
That is why the banks are reluctant to give accounts to people on short time ( read: tourist ) visas, and who only spend part of the year in Thailand.
Don’t expect to get a residence certificat, until you have stayed at a permanent adress in at least 3 month, since that is what the residence certificat should confirm.
Furthermore the added attention on whitewashing of money, is an added burden on the banks, so reluctant depositing large amounts isn’t a guaranteed way to open an account.
The value of a resident certificat, had gone down, since Immigration Officers are giving them to people that are not on a longterm visa, or have stayed severel months at 1 adress in Thailand, so even if it is a formal requirement, the bank make up their own assesment of the stability of the want-to-be customer.
Be aware there is a error in the start of the article ( and several other copy - paste media with the same article )
A Thai Bankaccount has never been a requirement to get DTV, on the contrary it has been one of the big advantage over other visa, that you could get DTV as long as you could show 500.000 Baht equivalent in any bank anywhere in the world.
It has never been the intention that DTV visaholders should be in need of a Thai bankaccount.
If choosing ED, you have to be actually studying full time, show up to all classes, and pass tests.
It is also depending on what to study, several people has gotten an ED visa instead of the DTV, if the ED is better suited to the reasons for applying i.e. studying Thai language.
As most that report about successful / rejection of applying for DTV, those reports is worthless without telling which Embassy was used, since there are so big differences between the different Embassies.
In the past there has been big problems with foreigners, that couldn’t pay hospitalbills etc. if they got involved in a accident.
Under corona you had to show a medical insurance to overcome that problem of unpaid medical bills, but that did also stir up a lot of criticism and other problems.
But medical bills wasn’t the only finacial problem to be dealt whit, where foreigners misused the hospitality of Thailand, and to make sure those who make the problem also pay to solve the problem, Thailand now request a cash deposit, to cover those situations.
And they know that you had that kind of money, when applyed.
That’s why the 500.000 Baht has to be readily available, and not locked in investment accounts or other accounts like that.
Read the requirements of the exact Embassy you will apply at, and follow them strictly, it trying to bend the rules, the risk of rejection will be higher, and thereby loosing the 10.000+ baht visafee.