There's one situation where bikes are next to impossible for a driver to see, and that's at night, stopped at a light in front of another car. Saw this again this week crossing a street on foot. I looked down the street & saw cars waiting for the light. Then something hit me...there was something funny about what I saw. Yep...THREE headlights...there was a bike in front of the car.
I was on foot and stopped, so I had time to digest the view and take another look. Dunno if a driver could have without active awareness that this can happen. Bikes are everywhere...look twice!
THIS situation, IMHO -- YMMV, is why I think "Loud pipes save lives." is a good thing. Wouldn't have happened if that was a big Harley!