I've heard of people stopped by the police before for holding up the traffic due to not keeping up with the speed limit (not sure if theres any specific legislation?). Unlike a moped these can't be easily overtaken in the same way.
Nothing more than a money making tool to get the under 20's to spend their money on driving.
The license will be cheap, the car is extortionate and the insurance will be murder. Yet, a whole year later, they will have to apply for their provisional and learn in a normal car. I can only see it as a money making exercise or some parents with money to burn keeping their children happy.