You might find this as odd, but when your scooter gets stolen, and its riding around say DC or PG, the police often don't have any way of knowing its stolen. Its not like they can run the tags and say "Hey, those tags says the vehicle is stolen" or "those tags don't belong to that scooter, they belong to a honda!" So there is an identification problem.
The insurance problem. There have been MANY accidents with these things and the lawsuits are starting to trickle through the system. The insurance companies all complained to the legislature because nobody can understand how scooters can ride on the roadway commonplace with vehicles and not have to have insurance. Bicycles primarily use other routes, (trails, bike lanes, etc), and do NOT use busy highways as primary routes. They are required to ride on the right most portion of the road when they do ride, and obey the same traffic laws as vehicles. Scooters however, can go anywhere on the road, they are required to have headlights, tail lamps, etc. They require their operators to have licenses, and everything else, but more than often, people aren't getting the required license to operate a scooter.
Enacting a helmet law will only bring down the deaths when these scooters get into an accident. Im sorry, but Univ of Md. shock trauma did a study on motorcyclists who were involved in crashes and wore helmets, and it showed that the full face helmet motorcyclists faired better and had a higher chance of survival than those with no helmet, half shell, open face helmets. Riding around without a helmet is just plain stupid, whether you feel its your right or not, if someone hits you, your dead- whether you were in the right or not. And most people aren't stopping nowadays when a crash occurs.
As for the old men with too many DUI's? Well, to operate a scooter you still have to have a license. If their license was suspended due to DUI, I would think that would prohibit them from operating a scooter? I don't know. And yes they can charge you with DUI on your own property, they can charge you with DUI on a 4 wheeler and even if you are riding a bicycle drunk, you can get a DUI in Maryland all of which will affect your license and driving/criminal record.