I mean the scooters like mopeds.
They are common in almost every country outside North America!
In Paris you see this beautiful girl, flowing dress, like out of a magazine - and she's on her moped! Out to dinner or whatever, it's normal.
They are cheap and they take up the same space as a bicycle. If SF made a few 'moped / bicycle' only streets, like a grid in downtown, where traffic just flew by and was fast ... maybe you'd see tons of people make the switch.