Regardless of where this woman was riding, she was hit from behind.  That puts the driver of the motor vehicle at fault.  It doesn't matter if she had flashing lights or mirrors or bright yellow spanx, the operator of the vehicle was at fault for the collision.

The driver now committed another crime by not stopping.  There is only one way that they would not know they hit something and that would require a high BAC or drugs.  Any vehicle operator incapable of knowing they hit a bicycle or dog or child, or even driving so close to 'brush' them with the wind blast is too ignorant to deserve the license they carry.

Fortunately for this woman, her luck was paid up.  Perhaps all cyclists who ride the roads should be required to wear body cams pointing both forward and rearward just as vehicle riders are required to wear seatbelts?  It could certainly provide evidence for prosecution or defense for all parties.