It all starts here with 2500 pounds for an average passenger car vs. 250 - 900 pounds for a street bike. Add the dimensions of a commercial van or fully loaded truck and there is no doubt which vehicle is massively dwarfed by the other.
Size is the major reason it's often difficult to see a motorcycle in traffic.
It's easy to figure. What motorcycles lack in pure size they make up for in ease and quickness of maneuverability. We're all taught as automobile drivers to stop for trains, watch for children crossing the street and use our lights at night. These are motoring basics. It's a fact of modern motoring that motorists and motorcyclists are certain to be sharing the roads in the future, more not less.