The problem I have with bikes on sidewalks is not when I'm walking, I have yet to encounter any who tried to run me over, even motorized. It's when driving, if the bike doesn't stop at every intersection to check for cars turning, and moves faster than a pedestrian it's just so dangerous. In the road at least the cars know you are there, you are the far right lane.

But the bike lanes here (most of them) are really awful too. I feel like they need train gates, those arms that come down, at intersections to prevent cars from turning while the bike has right of way crossing the intersection.