I didn't realize that the Smart was underperforming to the point that Merc is considering discontinuing them. I know the adoption of smaller city cars have never been all that large in NA, but they're doing exceptionally well overseas.
They are a perfect fit for European roads which make our bigger American vehicles look like army tanks barreling down the road. Much like other smaller cars they get that we don't.I think that most of the sales for the Smart have come from Europe, but I do still see a good number of them on the road here. Not sure how practical they would be for winter driving, and that's probably why they are considering something high riding to replace it.
It comes down to culture which goes so far back that are roads are influenced by it. Classic American motto is "Go Big or Go Home". Our roads are wider, drinks are bigger (7/11 big gulp), we have more cup holders (some passenger vehicles have 12-14), our people and of course our carNA's fascination with SUV's is odd, especially since most of them are being used as commuters with just one person on board. I think there is a misconception that they are safer, when in fact models like the Smart hold up quite well to crash tests.