Are convex side mirrors better than flat ones?

We bought our 2016 Subaru Forester, it’s our fifth, last October. I was shocked to find my driver’s side mirror does not show a true image of traffic, and the first few times I drove it I almost had an accident. Why would such a safe car, which is the reason we always buy Subaru have a dangerous side mirror? Could it be replaced by a normal one at Subaru expense?