Why do I need a letter from immigration to open a bank account after moving across Thailand?

After moving from Phrae to Mae Rim in Chiang Mai and completing the TM30 form, the user faced difficulties opening a bank account at a different branch of the same bank. They were informed that they needed a letter from immigration but were told that because the extension was issued in Phrae, they must return there to obtain the letter. Community comments highlight the confusion and inconvenience caused by this requirement, emphasizing that the change of address should have sufficed.