There are some areas in my town where I have to ride on the sidewalk, because the suburban moms who drive around can't seem to understand the concept of a bike lane. It's just a matter of my own personal safety at that point. As cyclists, I think that, unfortunately, it's up to us to be the alert ones. As long as you're doing what you're meant to be doing, no one should give you any trouble or hit you. If they do, though, you're going to be in much worse shape than they are. So just ride defensively if you're going through a busy area, and always be alert.