Originally Posted by
ItsJustMe
The general theory is if there are very few bikes on the road, drivers are not looking out for them. It's a clear and pretty well accepted fact that drivers get in the habit of only looking for things that they are expecting to see (that they see commonly) and miss unusual things (nobody needs to repost the basketball gorilla video, everyone's seen it). Also drivers don't know what to do around them and become unpredictable.
When cyclists are common, drivers are looking out for them and a common consensus about how to deal with them arises and drivers become predictable again.
Motorcycles are common and have been around forever, especially here in Florida, yet cage drivers still react to them unpredictably. The most common car/motorcycle accident is the left turn in front of the motorcycle and the car driver saying "I didn't see them" even with all motorcycles running daytime head lights. The psychological theory for this is that the human brain tends to discount movement of objects that are not considered a physical threat unless they are extremely unusual.
So auto drivers see other autos fairly well, they see big trucks very well.