The US is a big country. What works in a relatively micro system like The Netherlands (size of Maryland) or England (size of Louisiana) is a lot tougher to apply to the greater land area. There's a bigger audience to reach, and a lot of cultural barriers to get through, with each city seeming to have its own cycling etiquette or specific attitude towards cyclists.
In Portland, I would say that the
majority of cyclists obey traffic laws -- stopping at stop signs and red lights, signalling, etc. There is plenty of support for the bicycle culture, and a "do your part" attitude. I've still seen people running signs on occasion, but it's usually pretty easy to tell who is experienced in the area and who just grabbed a bicycle and is winging it, plus, bicycle law breakers tend to get "called out" more by their fellow cyclists. Head off to San Francisco, and it's still a bicycle friendly city, with the major change of it being that it is also somehow a place where cyclists routinely fly through stop signs. It's an interesting contradiction; a large cycling community with often bad behavior, but with a motorist acceptance of bicycle behaviors that make it a safe city to travel. Drop off the "bicycle friendly cities" list [
http://www.huffingtonpost.com/2010/04/08/20-most-bike-friendly-cit_n_530186.html#s79376 ] and it gets worse.
In many Southern cities cycling is something that people do not want to see. You start hearing about people who think that streets should be off-limits to cyclists, and the few local cyclists that the city has end up making huge commuter detours just to get to the same place. New Orleans, for instance, someone in the above link called "bicycle friendly" because there are bike paths on the river and lake fronts. Segregation is not bicycle-friendly. If you
have to use segregated roads for travel then your options are limited. Imagine what that does to a local's psyche. They grow up thinking, "Oh yeah, bicycling is fine -- just go to the river-front to do it." What you end up with is a cyclist who sells themself short. In a place where bicycles and cars are rarely on the road together, there's not enough interaction for cyclists to even realize that stop-signs apply -- it's still just a leisurely activity minimized to sunny, weekend rides. For drivers that same lack of interaction can lead to the old imposed class prejudice against the smaller vehicle. That's the cultural barrier that people can be up against when there's no community. And it just degrades. That means no funding for bike lanes, no bike awareness campaigns, and very little progress. All there ends up being is cyclists "winging it," motorists getting angry, and politicians being powerless to affect change in that environment.
Too long, yeah, so here's the wrap-up; again, it's the elementary school message: "Do your part." I don't think pure motorists (non-cyclists) visit here often, so for the leisure cyclists: don't go halfway. Don't dismiss it by saying, "it's okay on certain roads;" pick your battles, sure, but look around at the cultural impact that your area is producing, and ask if you're contributing to a prejudice. Ride, and ride often. Obey the laws, correct fellow cyclists (not from behind the wheel of a big truck, and be friendly about it), "thank you" wave the good drivers, and when you get out there, see yourself as an ambassador of the sport.