In N.C., small motorbikes and scooters below a certain cc engine capacity, aren't covered by standard licensing law -- or so I interpret from their appearance on the road near the shoulder now and then, without license plates. They're dangerous in regular traffic, but I guess for people who need to get to work, they are the only alternative. They barely keep up with traffic, but probably are a little faster than lawnmowers.
I hope your neighbor can beat his habit and survive his lapses. It's funny, but dangerous to him.