In Washington State this depends heavily on municipality and you need to know exactly which cities you're riding through. State law only says that you have the same duties and rights as a driver when on the road, and that you have the same duties and rights as a pedestrian when on the sidewalk. When I rode to work I checked all three of the cities I rode though and they all allowed bicycles on sidewalks.
I generally choose whew to ride based on the density of traffic. If nobody is on the sidewalk and the sidewalk is in good condition I'll ride on the sidewalk.
I feel much safer in an environment where there are clear rules of engagement that are, by and large, respected.
(Anecdote: my most recent crash was with a scooter, the rider of which was very inexperienced in traffic and reacted to a tight spot by doing exactly the opposite of what they teach you in driver's ed. Feel free to guess whether this was on the road or on a bike path...)
> I consider pedestrians to have just the responsibility of paying attention to their surroundings
This is what I'm talking about. Many people cannot even be bothered to do that. If you aren't going to take an interest in your own safety, why should anyone else? The sidewalk is not the place to zone out and lose yourself in your Twitter feed.
No, because the law states that a bike on the road with cars is equal to other vehicles and has no higher priority in regards to right of way.
In contrast, a biker on a sidewalk is not considered equal to a pedestrian. In fact, it is illegal in most cases, but probably not illegal or dangerous enough to warrant strict enforcement.
I consider pedestrians to have just the responsibility of paying attention to their surroundings to not inconvenience other pedestrians, not bikes or scooters.