Are we replacing drivers though, or just adding a new threat to our streets on top of existing ones.
Here in London at least, scooter journeys are mostly impractical by private car due to lack of parking. Logically they are replacing bus journeys, walking, taxis and cycling.
the point is that there is an emerging new threat.
aside : i'd like to see this world of yours where cars are operated 100% legally -- even very responsible drivers tend to violate some road laws on a fairly common basis.
Drivers operating cars 100% legally are a bigger threat to pedestrians than reckless scooter users.