It might indeed be the case that there are no Dutch versions of the game available in the USA, so that they sent you the only available language version. Vstep does it's own distribution in Holland, and I suspect the Dutch version is only available here, in Holland (and Belgium, since they speak Dutch in Flanders.)
You can take this up with Vstep directly if you wish, to ask wether or not this is the case.
info@shipsim.com
Regards,
Fred