The only natural predator of the motorcyclist.
The term for a cager
that's oblivious to other road users. Sometimes due to inherent lack of skill, though often due to multitasking and committing insufficient attention and/or resources to the driving task.
Tasks competing for the cager's mental capacity often include one or more of: operation of cellphones, application of makeup, reading, eating, drinking, smoking, admonishment of offspring, retrieval of CDs...
A correlation has been noted between the level of irresponsability of the BDC and the sense of invulnerability conveyed by the size and weight of the SUV she drives.
BDC on the phone, yelling at her kids in the backseat pulled out in front of me. Bitch now has a size 11 dent in her passenger door.