Most cyclists wouldn't be riding on the sidewalk if they had proper infrastructure.
If you look at both DC and NYC they reduced the incidence of cyclists on sidewalks by implementing dedicated bike lanes.
When I drive in the 'burbs, it's hardly surprising to see cyclists who prefer to ride on sidewalks lacking pedestrians over riding on a two laned road with cars going 70km/hr.
It's clearly a design problem, not a problem of cyclists with a bad mentality or behavior. At least where I live, drivers who kill cyclists get extremely light sentences (if any), so is it any surprise that in certain situations, cyclists will opt for self preservation?
I say this as a person who predominantly drives. Even as a driver I think any cyclist who cycles on a major road without a bike lane has some major guts.
