The things are everywhere around Seattle, so many that I've quit waving. There are four in the parking lot at work, including mine, and our company has less than 100 people.
Visiting my parents in Lakeland, FL for a week? I saw one parked in a guy's garage in their neighborhood, that's it. I'll see a half dozen Leaf's just on an eight mile drive to work on any given day. So it seems it could be geographically specific.