Changing money - different countries, different experiences...

We usually don't change money a lot. We prefer to use ATM's which is safer, especially in countries where there's false money around (like China).
Sometimes though, we have some leftover currency that we have to change. In Seoul, we wanted to change some leftover yen. We went to a shopping centre where there was an exchange counter, and our yen were changed into won. About 30 seconds. Freshly off the boat in China, we had some won left but no yuan. Changing the (ridiculous) amount of won on the black market in the street took less than a minute. Waiting at the border between Vietnam and Cambodia, a woman carrying a big wad of money changed our leftover dong into riel, a matter of a few seconds. And yes, I did change some dollars into baht at the Cambodia-Thailand border at a very bad rate...
So, usually, not very time-consuming. Except the one time we went to a Chinese bank....
Nanning was the last Chinese town we visited before heading to Vietnam. We had quite a few yuan left and wanted some cash in dollars (which is the unofficial second currency in Cambodia and also widely accepted in Vietnam). So we went to the Bank of China. The big main branch was closed for lunch, nobody there except a sleeping bank employee. We found a smaller branch that was open. Changing money should be quite straightforward in the biggest bank of China, shouldn't it?
At the first counter the accountant told us to go to the next counter (probably she didn't speak english or was just too shy to speak english). Her colleague was nice but got a bit nervous when we said we wanted to change yuan into USD.
First, I had to show my passport. He copied some data down, then asked what country I was from, apologizing and saying that he wasn't used to exchanging foreign currencies. The amount of yuan was worth about 130 USD. I had to show a proof of where the money had come from. I went tense just a fraction of a second... then I remembered that I always keep my ATM receipts, and I did have the last one. I gave it to him and he gave it to his colleague who went to make a phone call (to verify whatever the Chinese always want to verify... probably just showing that they're doing something). After this, I had to go to a table in the hallway to get a photocopy of my passport and to fill in a document in 3 copies (which I had to fill in twice because I got it wrong the first time...), saying where the money came from (I just wrote "ATM"). With all this I went back to the counter where he did some typing on a computer and some printing. This had been going on for about 40 minutes... fortunately there was airconditioning!
And finally (I couldn't believe it) he opened his big money drawer and took out the dollars.

The Chinese definitely love paper...