well without getting too political... it is simply a matter of currencies values being based on the value of other currencies rather than being based on economic data... since the US dollar is currently the most used currency for international trade it has more buying power even if its value is less... which is why a set can be about 10 euros or 10 dollars... even though by exchange rates (which include a surcharge for obtaining the other currency whether you physically get that currency or not) indicate otherwise... for example the Canadian dollar has been worth "more" than the American dollar for a while (until the last few weeks) but the US prices compared to Canadian prices are almost always lower...
that might be a complicated explanation... but I only know how to make it more complicated, not less...
That is what happens when everybody is off the Gold Standard...
SO in short, it isn't really a discount, it just looks like it on paper... because we compare the prices between countries more than ever
Also, there are other cost factors to be considered in each market... there may be additional costs associated with selling the items in europe that do not exist in the US... I'd have to see the full financial documents to know for sure...