Where are you? I've never seen one on the roads here.
I find the US restrictions on smaller vehicles baffling.. especially since one can take a motorcycle out on any road. They certainly aren't 'safety rated'. But put a cockpit around it and suddenly it's not 'safe'.
I guess not, if an oversized SUV were to hit it, but again, if a motorbike is OK, why not what amounts to a motorbike with an aeroshell around it?