I guess I'm not as assertive as you guys... I rarely take a full lane, only if the street is so narrow that there's no way I can be safely overtaken. Otherwise, I leave it to the drivers's judgement when and where they pass me. I leave myself some bailout room at the side, riding 2 feet from the edge.
It's definitely NOT because drivers are more skilled and cautious here. More like, if I took the lane, they'd hit me intentionally.