Piaggio, the Vespa's manufacturer, also made a line of miniature scooter-trucks, ideally adapted for narrow Italian town streets that had in the past been trod by donkey carts or similar; occasionally one sees one outside of Italy (I once saw one in West London; the poor thing must have gotten terribly lost), though they don't seem to have caught on in a big way there. It could be argued that post-war Italy had a two-stroke engine-led recovery.
As revolutionary as compact, stylish-looking and affordable scooters were in the post-war years, they can't help but look a bit dated. They're noisy, bulky, relatively inefficient (technology having moved on since then), and consume Saudi Arabia's Finest, which probably isn't going to get any cheaper. Though Piaggio are now testing a hybrid Vespa in Milan; the new model can run off either petrol or electricity, much like a Prius, or can be plugged into the mains if you'd prefer to give the House of Saud the finger. The "electric-only" mode is still said to be slower than the petrol-powered mode, though one presumably doesn't buy a scooter for raw power.