I have asked my vietnamese colleagues about this, and they told me that they do a lot of their regular transactions, transfering amounts of money or putting money into their savings accounts, by ATM.
This means that if you are standing in line behind a person doing what you described in your e mail, he or she is probably just paying the monthly bills, checking if the salary came in yet, checking the balance and oh yes, withdrawing some money.
On some ATM's there are also promotions that can be 'clicked on' and read, so they do that as well.
I have asked once or twice if I could quickly just withdraw some cash (for instance when I had the taxi waiting for me or when I was just in a hurry), and was given the ATM with a friendly smile.
That is the nice thing about Vietnam, people here are usually willing to be understanding if somebody else is in a hurry.
A couple of younger, college-age friends of mine have also said that since ATMs are relatively new, some people take longer because they are inexperienced with the machines. That's just some people, though.
Like 4inhanoi said, some people do all their banking transactions (on multiple accounts) at ATMs.
answered about 5 months ago by Alexis

Naga is right. Most of the ATM deliver a maximum amount of 2 millions VND. When you are about to purchase a motorbike for, say, 28 millions, you have to withdraw 14 times from the ATM. Most of the transactions (even large ones) take place in cash, here...