RE: Is stealing a street sign a felony?
With an unguared intersection, you are supposed to yield to the person on your right, at least in WA state you do. I've seen problem areas where accidents frequently occurred because most people don't think about yielding when there is no yield sign or stop sign. Eventually, they put up stops signs. I know of a few different areas where signs and signals had to be installed, even those dreaded "roundabouts".
So a missing stop sign can create essentially the same scenario, an unguarded intersection, although the speed involved in areas of unguarded intersections surely differs from high-traffic, higher speed areas guarded with stop signs. I don't think you can say a driver was negligent for not yielding when there wasn't a stop sign (where there used to be one), but that's not to say an intelligent, defensive driver couldn't have avoided the accident.
Kale