Markets tend to be regional for many reasons and most smallish businesses do not have the skills to be outside of their markets. I doubt the Clueless Wonder has ever priced international shipping rates, duties, and delivery. One can sell from the US to anywhere in the world, theoretically, but practically it's a bit more problematic for physical goods.
In the US, Amazon does 1 or 2 shipping to me (Atlanta) from Lexington, Kentucky. Lexington is about 6 hours from me by car. So shipping an individual package via USPS, UPS, or FED EX is practical and reasonable to someone in the Atlanta area. It may go by truck (lorry) or by air. Now to ship to Asia one has to factor in either a ~12+ hour flight or being on the water for ~6 weeks. I think anyone in Asia is going to purchase from a local operation just for the convenience of a reasonable delivery.
Shipping rates are based on distance, weight/size, and general aggravation. Distance is obvious, more fuel and time is needed to go a far away place than one near by. Weight/size has to do with the vehicle has a both a maximum volume and weight it can handle before it is full. The general aggravation is individual retail packages require excellent carrier logistics to get to the correct customer and this costs money for the infrastructure to track the packages.
Duties can range from minimal to horrendous depending on the goods and the rate is based on the invoice value of the shipment. But would need to check local laws of every country one is shipping to and applicable trade agreements between the countries involved. If one gets the idea that this can be a nasty thicket, you are correct. I have done imports from Germany to the US and have some idea of the nastiness involved.
The net effect of all these issues is make retail sales very regional and often country specific. Once an importer has the goods in the country at wholesale the retail channels can very efficiently distribute them.