The Japanese originally took the Subway Train Rings / Handles you find on the trains / trams, so when passengers have to stand, they have something to hold onto.
To show how low the car is... The lower the Train Ring is towards the ground = Shakotan Style.
Popular with Bosozoku Members, but no one, other than Japan runs Bosozoku.
In general, the western world think its cool to hang anything from the towhook.
*shrugs*