The customs forms are a giant pain in the ass to fill out. They make you enter both addresses, which would normally not be a problem except for the need to put each letter in its own box, which is obnoxious.
You're right though, the actual declaration is super easy.
Except when it isn't. Or when the foreign country disagrees with you on the value of the item. Or just flat refuses to accept the package for whatever reason. Or accepts the package, then blackholes it.
Seriously though, it's significantly more complex to ship a package overseas from the US. Domestic mail is fairly easy to account for, but once it leaves the US Postal system, all bets are off. We can't even get official delivery of comfirmation for less than $20, and that was on a LETTER!
To ship a keyboard, even to western Europe, costs at least $30. And that was a fairly light model. To ship a Model M would be quite a bit more, and that's bare bones shipping, no insurance, no tracking, nothing. For even tracking, it was nearly $100 for that keyboard.
So it isn't xenophobia or idiocy. A lot of times it's just a desire to avoid filling out extra paperwork. Other times it's a desire to avoid complaints of "shipping is HOW MUCH? Nevermind", and then losing the sale. And that doesn't even bring us to the frustration of lost international shipments, or buyers that claim to have never received an item, because they know you can't track it, etc.
Edit: I don't mean to imply non-Americans are more likely to scam than Americans. What I meant was that it is usually easier for them to do so to an American seller, due to the lack of information. Further, many scammers on eBay actually claim to be international, hence the blanket ban of all international shoppers. It's unfortunate, but the sellers are allowed to protect themselves.
