I would assume this is just the classic supply and demand scenario. It's simply markets. I know that, in Great Britain, Levis blue jeans (made in America) cause much more than they do in America. There are many reasons why, including tariffs, but that's just how it turns out.
Also, I do believe that NI is working to change the situation, though I could be wrong. I know they recently opened up a manufacturing facility in Europe to help drive down costs. How much? I don't know. But it may help.
J.R. Allen