I think it's mainly a 'ride on weekends, afraid of cars' vs a 'aware that cars, generally, exist' thing.

Crap, ride in a straight line, be responsible for being aware of what's around you, call out things that are exceptional, and if you're in front, don't lead the group over the dead squirrel.

Seems like a lot of the problem is people thinking they have to ride in the gutter instead of in the lane.