I have to chime in. I grew up on a ranch, and learned to drive a tractor around 7 or 8, by sitting on my grandfather's lap while he let me drive. After some lessons, I was allowed to drive myself, with him on the tractor with me. By the summer I was 9, I was doing all the plowing and discing to prepare ground for winter oats for cattle.
At 10, I was raking hay, and by the summer I was 11, I would cut hay in the morning, rake and bale in the afternoon (the hay that I cut the day before), and then drive the tractor so dad and grandpa could load the bales to go to the barn after they got home from town jobs.
Was it perfectly safe? No, it wasn't. But I had grown up around machinery, had seen injuries (at 8, I drove my grandfather to the emergency room in town while he held pressure on a bad cut on his hand, which he received when a cow caught the hand between a horn and a fence post). Was this safe? Some would say no, but as my grandfather told the doctor at the hospital, I got him there, and since there was no ambulance service available, I was the only option.
Now, before someone chimes in as to why there was no ambulance service, the only ambulance in town was operated by the local funeral home. They had a funeral with a burial about 40 miles away, and they were all tied up with that. Times were certainly different back then.
I am starting to ramble, but, yes the kid on the tractor is a dangerous situation, but he is on the right side. A square baler like this is operated at low ground speed, and since you look back on the right side to watch the pickup, if he should fall off, the operator will more than likely see the movement with his peripheral vision in time to stop. It is dangerous, but probably less dangerous than even letting him ride a skateboard.
I know that the some are already lighting the flamethrowers, so fire away.