There are a lot of scams online. Many people are very cautious and value reputation established over time. Nothing personal.
I live outside of the USA and get very tired of internet posts that state something like "US only" therefore ignoring 96% of the world. Bit there's not much anyone can do to change such a mindset
I understand your frustration, but I'm often one of those people. I used to get inquiries all the time from people asking about shipping to some far off land. I'd do the research of how much it might cost (hint, a lot!) let them know and then they don't get back to you or stop paying. I've had it that someone tried to scam me by sending me fake e-mails from PayPal. Its often just not worth it.
eBay now has this feature where they pay eBay for the extra shipping and I send my goods to someplace in the USA and they take care of delivering it to Uzbekistan. That I have no issue with. Otherwise, for lots of things, its just not worth the hassle for the occasional buyer who might be elsewhere.
That said, I've never tried to sell anything through these forums and I'd probably moderate my stance if I did.