Yes, this is more than one time I have seen a vehicle that is not a kart standing out in the open while a kart race was going. Unfortunately, I was not at any of these events. If I had, I would be the first one to stop any on-track action until something was done.
Every event I go to now, I review run-off areas around the track, and try to address them with the track owner/promoter if I feel there is something dangerous and a potential danger.
Every racer, when doing their track walk, needs to take some time to look at run off room, and be sure there is nothing that you or someone you are racing with, could come into contact with.