You know, I'm going to assume that ALL of these drivers have some sort of radio communication with their pits. Maybe that is naive, but if they do, couldn't they also have a sort of emergency channel that they could monitor as well? Something where a big booming 'voice of God' would override the normal pit chatter and say stuff like "Caution turn 3" or "Stalled car on the grid"...
These don't appear to be low budget cars or teams... I know on many of the Nascar circuits the driver can only see so far around the turns, and at the speed they are traveling, they rely on their own team to have spotters that sit there watching for trouble up ahead and to give the driver a heads up.