As a scooterist, (yes, I made it up. Motor cycle owners get cyclists. I have a right) do I have an obligation to wave to other scooterists? I've ridden that scooter for, however long, and never really thought of this. Then again, the thought occurred when a scooterists uh.... scooted by. Is there an unwritten law that it is polite to wave to other scooterists?
Then again, you don't see car drivers waving to eachother right and left just because a car passed by. Maybe, scooterists do it because we are a minority and need to show each other "Hey, don't worry, you aint't the only scooter rider out there."
I'll remember to wave next time. :)