Khakha, Dear my friend!
I believe if you learn about it, you will have the answer.
My own thinking: The USD exchange restriction aims to helping the government to control foreign currency more & restrict people to store USD this will help banks mobilize USD easier.
Allowing 7 provinces to use the Yuan, helping to exchange goods more favorably but it will have many implications and this also is unconstitutional. :(
About ATM, there are more, but withdrawals from ATMs are very troublesome. You can withdraw up to 5million VND or 2million VND (if different from the bank) and may have to wait long or the ATM will run out of money.
Azaza :(