Part of the trouble is that street markings do not reflect car traffic or other special circumstances. In NW Seattle, for example, Fremont Ave (Blue or "least safe") is one of the best north/south corridors, because car traffic is light and supposedly has to turn at every major cross street. Bikes ride in the lane of traffic, reducing unsafe passing.
In comparison, Greenwood Ave (rated Orange, or "ok") has much higher car traffic and the painted bike lane runs in a door zone.
Anyway, Seattle doesn't really have any "green" bike infrastructure. If it did, this kind of map might be a lot more useful. In Seattle, I have to choose between "blue" or "orange." My highest priorities for bike safe routes include low car traffic and no door-zone bike lanes, and the separate painted lane is less important.
It seems that a lot of the time, painted lanes are added to the busiest streets. Especially on the eastside, I wouldn't suggest riding on any of the marked routes on Mapzen.