After watching some video of catapult robots at our recent competition a question came to mind: if a robot shoots a ball (any size) over the wall and it either bounces off the ground and hits a driver/coach, or directly hits a driver/coach, then bounces back inside the playing field, what would be done to the ball? The referees can’t walk into the field and pluck the ball out of a group of robots, and it may be illogical to keep track of the offending ball, especially if more than one ball is bouncing off humans.
Since <G4> states:
‘Balls that leave the playing field are considered out of play. These objects will NOT be returned to the field.’
and <SG3> states:
‘…Accidental contact will not be penalized, unless the contact directly impacts the final score of the match. This type of accidental contact will result in a disqualification’
Clearly this rule is designed to prevent driveteam members from intentionally impacting the result of the match through physical interaction with the field objects, game objects and robots.
It is the accidental contact that becomes more murky. The reason the accidental contact part was written into the rule was because teams would often extend their hands and/or antennae over the playing field which would accidentally make contact with game/field objects on the field and in rare circumstances impact the final score of the match. Even though this type of contact was accidental, it was giving the alliance an unfair advantage, thus needed to be penalized. The intent of the rule was that team were responsible for any contact between driveteam members and field/game objects that occurred on or over the playing field.
In the case you have described, the contact has occurred off the playing field. Any accidental contact with game objects that were to happen off the playing would not be penalized by <SG3>.
Next is the issue of balls being accidentally returned to play by bouncing off either a person or some object that is outside the field. As you stated in your question, it would be inherently unsafe for field personnel to try and remove balls from the field during the match. Also having the referees try and keep track of the ball would be both illogical and infeasible. Thus any ball which is accidentally returned in the manner described would stay in play.
In summation, if a ball bounces off a driveteam member and back into play, nothing happens, play proceeds as if the ball never left the field.