I don't know of any high end diecast cars ever manufactured in the US, they have been made somewhere else pretty much since the beginning, even the low end toy variety. How much more would it cost to make them here? I think we all know the answer to that, way too much for any meaningful sales. Too many reasons that we are all aware of, so the obvious answer is to find another source of cheap labor and no unions/pensions/401Ks paid holidays etc. to have to worry about - and quit giving China more cash for their already huge war machine. It's the American way.
-MJS