[svxistentialist]

Nobody knows.

There has been speculation here that this decision related to the need for some US states to dyno test the cars for emissions testing, and enabling the 2WD mode by removing the fuse bit in the cheaper transmission facilitated this.

Another possible scenario is cost; the US was a volume market for Subaru, but the prices charged for the SVX in markets that got the Japanese VTD box is actually double or more than what US buyers would be prepared to pay. So the logic is Fuji saved unit costs by using the cheaper rear assist transmission in low profit high volume markets. This argument carries weight because these "high cost" markets for the SVX had enough of a profit margin built in to cover the cost of what Americans would think of as "fully loaded" specification. These markets got everything included in the price except motorised 4WS and closing mirrors.

However, Germany, which is also a high spec fully loaded market, they also got the US type rear assist transmission, so maybe the dyno / emissions testing first scenario is what dictated the selection.

We may never know.