When 50 other cars are nearby actively communicating with each other about the road conditions that they each see, only a representative subset of those cars need to correctly identify road conditions and report them to the entire group as a road-conditions map. Cars in the group validate the observations and risk-factors reported by other cars. Then each car independently makes its driving decisions based on this shared-data based on its relative position in the group.
In this way, being surrounded by hundreds of other cars is a plus, and leads to more data by which to determine safe self-driving behavior.