Mark S wrote: "the biggest difference between riding a bicycle in North America and in those cities thought of as 'cycle friendly' such as Amsterdam or Copenhagen is not so much infrastructure per se, but rather the attitude of most motorists"
That's it in a nutshell. Attitude trumps everything, including law. We have laws in place to protect the rights of bicyclists, but they're not enforced and in many cases police don't even know the laws. (or they do and choose to ignore them)
Read what Pleasanton police Sgt Leong said in the death of a rider who was hit along with her husband on Foothill Road:
"One factor in the investigation is whether the Hersevoorts were riding side by side or one behind the other on Foothill, and whether they were both in the bike lane alongside the two-lane road" The road has a shoulder, by the way, not a bike lane.