Who's fault? I'm sure for the motorcycle driver (or his survivors), it doesn't matter. Motorcycles are so inherently unsafe in urban/congested areas, I don't know why anyone without a death wish drives them there. By all means, if you want to, go right ahead - but this is what can (and usually does) happen.
Here in central FL, we have so many elderly people that have terrible reflexes, poor hearing, and abysmal vision - not to mention cognitive deficits - that driving a car among them is dangerous. I see these cruiser bikes with no exhaust or Sampson pipes sporting stickers "loud pipes save lives", and I scratch my head. If being such an unprotected, small, and all but invisible target is so dangerous that you have to drive with the equivalent of your horn blasting 100% of the time, perhaps it's time to pick another form of transportation.