Predam iPhones

I’ve been coming across this term “predam iPhone” recently. If you do a Google search for Predam iPhone you quickly get this idea that it is an unlocked iPhone. Sometimes it is spelled “prodam iPhone.” It is a strange word, at any rate.
Apparently you can buy them on eBay, or from all sorts of weird sources. They even come in huge quantities, like I’ve seen pictures of a whole palette filled with these things. I found one source that says that predam means “break” or “unlocked” and I’m guessing that these are found in a lot of black markets in countries that don’t have the iPhone yet.
This did get me thinking as to why Apple still only sells iPhones in Apple and AT&T stores. Why not on Amazon.com, Best Buy and those multi-brand mobile phone stores? After all, Apple needs to reach that 10 million goal by the end of the year. More stores can only help.
I was recently in an Apple store and I overheard people who were not Mac fanboys like me talking about “Have you seen the iPhone? It is so cool! I think I need to get one. Me too!” etc. I think that salesfolk at mobile phone stores and electronics stores would love to push a $400-$500 device that practically sells itself.
Now, the reasoning I thought that Apple was going with to not sell in other stores was the unlocking problem. They wanted to keep close tabs on each iPhone that goes out the door. But obviously that is not working if there are so many unlocked iPhones floating around, and pages of “predam iPhones” are clogging the net.