Results: Why is it so hard to exchange currency from one country to another?

So my husband and I have been traveling internationally a lot. Thus we have a need for money other than the good ol' US dollar. Since we live in a small town, our local bank doesn't have the capability to exchange currency. What to do, what to do, what to do?

One option we found is to throw ourselves on the mercy of unsuspecting bank customers in foreign countries. How this works is - we walk up to someone in a major bank. We politely tell them we have only American money. Would they please help us exchange it for local currency? Amazingly enough only one person has turned us down so far and that was when we were in Canada. So would you help someone in this situation?

As a side note - have you ever thought about why there are so many different currencies in the world? Wouldn't it be nice if there was only one? Or at the very least, if businesses would take all legal forms of tender, not just what their country uses? Let's face it, you can google the current exchange rates in five seconds flat. You can add any comments below.