Nope, in fact most of them mount one or more of the engines sold in the US for their counterparts, so emissions isn’t a reason. Neither is safety, as most of them were originally designed with half an eye towards US introduction.
No, the reason why we don’t get them here is because of corporate and UAW stupidity. There are a couple of models I didn’t list that we *are* getting here (as Saturns), but they are so watered down “for the American consumer” and so badly made by the UAW that nobody wants them.
AH....so it’s the “unions”....er....government!