>Bicycle paths on walkways are also hazardous to cyclists - and stressful
I never said they were great, just better than riding alongside cars. I ride on walkways every single day here in Tokyo, frequently very, very, very close to pedestrians; it IS stressful trying to dodge the chaos of pedestrians and also other cyclists who are all crammed together on narrow sidewalks. It's still better and safer than riding with cars, which is why all the other cyclists here (esp. mothers with children) do it too.
>but most cars do pay attention and try not to hit you
It doesn't matter: just one car not paying attention will likely kill you, or at least cause lifelong injuries. Running into a pedestrian is not at all likely to cause such trauma: the masses and the speeds are both far, far less.