Roadways have to conform to engineering codes and the important one in this case is visibilty. For sidewalks anything goes. Unfortunately bike paths are also usually anything goes.
If you want to claim that you have a spot where there's an exception to the rule be my guest. I break rules too. Just be aware that behind every tree and fence and shrub there is unpredictable and random interference and that your available reaction time is one small fraction of what it might be in a more standard right of way. I call sidewalk riders ER admissions.

As far as I know, roadways do not have to conform to any standards regarding bicycle traffic. Sidewalks that are straight and unobstructed by any of the things you describe are vastly safer for the bicyclist than the high traffic roads that I am referring to. Obviously a level of care is needed wherever one rides. I have been bicycling for over 40 years without ever colliding with a pedestrian and the only serious accident I ever had was misjudging some railroad tracks. The choice for sidewalk riding in the case I describe was more than obvious to me, maybe it would have been different to you. My point is that it is inappropriate to cast moral aspersions on a bicyclist who judges it better to 'hit the sidewalks' especially without knowing anything at all about the context.

Moral aspersions? I don't think we are talking morality here, but rather what is safe and appropriate. I agree with "Old Hippie", that sidewalk cycling is not nearly as safe as many people suppose it to be. But I'm sure you're right, ET, to point out that conditions vary from place to place. Fortunately I live in a town where cyclists have asserted their right to be on the road. So, I would never consider using the sidewalk.

Okay, you guys come to my city and ride the four lane to my workplace where speeds exceed 50 mph on a daily basis and tell me how 'safe' that is.

Nuff said.

What city is it? If it's close, I might. I bike on five lane arterials every day. Everybody who doesn't bike in traffic thinks their roads are too dangerous for it.