Like on MUPS, pedestrians have the undisputed right-of-way on a sidewalk. That means if you hit one, you are liable for damages and injury, no matter what dumb thing they did to precipitate the collision. My advice would be to avoid sidewalks for reasons of liability unless you can absolutely guarantee that there is no foot traffic anywhere near.
If Michigan is like other places, state vehicle code *seems* to imply that they are allowed on sidewalks, although local ordinances may prohibit them in certain areas.