Just for the fun of it I queried the Ohio BMV about the number of smart fortwos registered in the state: 2771.
The real question is why does only a small fraction of this number ever show up for anything?
I live in the Wiloughby-Eastlake area. I only see maybe 1 or 2 other fortwos a week. In fact, I have never even spoken to another owner. Doesn't answer your question but I wonder how many others have a similar story.