Originally when released Vespa's and Lambretta's didn't have mirrors, then the Gov. brought in a legislation stating all road vehicles should have at least 2 mirrors. Mods pretty much saw this as a chance to take the piss and went bezerk with mirrors and lamps. Hence the mod trend of crazy amounts of lights and mirrors
I'm not a fan of the mirrored up scooters but when I was younger, my uncle had a Lamb. Gt200 an spent some serious money on performance upgrades, had slight headwork done along with some carb work and airflow work to the manifolds. It flew! Was a cool looking thing too, I'll try and find a few pictures of it which I'm sure he'll have, only sold it not long ago, had it for years an years!