Depends -- my dad is a huge HUGE Star Wars collector. And even when I was young, I used to keep everything in pristine condition because I learned from my dad that if you did that, and you decided to keep it you'd appreciate having it nice, or if you sold it you would get more money for it.
I collect Ghostbusters figures and did as a kid. In fact, I asked my dad if the first one I got I should open or keep sealed! And I was like four or five. It got opened, but I very carefully took off the bubble that held it and still have the card in perfect condition today. All of the video games that I own are in the same condition today, regardless if they were 2600 games that I bought or NES games -- if they were new, they are more mint than any game I have ever bought used from anywhere else, period. So, again -- depending on the person, it's reasonable that this person kept it so nice.
No, because if that was true someone would have found one overseas if they were way more common over there.
I really believe that these were sample games that they paid a lot to make the mold so they could make a ton of money after stores bought it. They did the mold to set their product apart and show that it was a serious thing. And then they made the cartridges and sent them to corporate buyers -- maybe 100, maybe 1000 copies.
After that happened, they never got enough orders to justify a run of the game for real. Most buyers threw the games out, but a few got saved, which are what pops up.
That's the only story that makes sense to me, but the fact it is such a WTF thing, as well as that no one knows, it will continue to drive tons of interest in this game above just about any other classic game out there.