In February, we reduced the visibility of UK items on eBay.com, as they had reached a level where they were significantly impeding domestic trade on eBay.com. We are aware that a small percentage of sellers, who relied in whole or in part on US buyers, were significantly affected by this reduced visibility.
Since then, we have been planning how best to display some UK items on eBay.com and some US items on eBay.co.uk so that cross-border trade can thrive without impeding domestic trade on either site.
It seems to me that there are several ways to read this. One is that US sellers are worried about competition - especially with the slipping $ to £ and $ to € rate of exchange. References to 'impeding domestic trade' tend to reinforce that interpretation.
On the other hand I've noticed - for example on Etsy - that many US sellers seem frightened of selling internationally. Having looked at the US Postal Service Web site I can see why. Sending anything out of the US seems to be a bureaucratic nightmare.
Some US sellers however seem almost to be unaware that there are people outside the US borders who actually buy things. This shows up a great deal in forum discussions of all sorts. I remember being accused of being 'Unamerican' back in the days when I had an AOL e-mail address for example, the person concerned clearly having no idea that AOL was an international company. I suppose, given the huge size of the USA, this isn't entirely surprising, since making any international journey takes much greater effort than travelling within Europe.
EDIT: It occurs to me that it is always possible for the buyer to exclude non-local sellers so I suspect my less charitable conclusion has some merit.