In my experience—at least in Seattle which is more bike friendly than baseline in the US but certainly not on par with Portland—drivers are far more likely to yield to cyclists with these markings than where a bike lane is present. In contrast, I’ve had drivers try to run me off the road, screaming mad, when I had the gall to perfectly legally ride in the main road where a bike lane was present[2]. Even when there was plenty of space for them to pass.
1: https://en.m.wikipedia.org/wiki/Shared_lane_marking
2: Several of my cyclist friends disagree with me on this, but I find the particular bike lane exceedingly dangerous. I frequently avoided it when it was on my daily commute route, after numerous frightening close calls. Riding along with the aggressive drivers really did feel safer.