Im a mum of 2 !! Although both too young to ride at the moment, if or when they do ride a bike i'd want to know that the bike they are riding can keep up with main traffic !
If your teen can't maintain speeds similar to the mainstream traffic other road users WILL become impatient, and this is when accidents can and will happen !
In my honest opinion your teen will be safer on the rs than a bike / scooter with a top speed of less than 60 !