safety is not black and white. My kids work with me all the time and sometimes this means being on the tractor. I take every precaution to work safely with them and they have never gotten hurt while working with me. They frequently get hurt playing on swings, sleding, playing tag and doing all sorts of kid things.
For all those people who think a kid shouldn't be on a tractor, do you also think they shouldn't swing, sled, climb trees, ride in a car??? I'd love to see a risk analysis of these activities compared to riding the tractor with Dad. At least in my household, I already know that swings, sleds, and trees are all more dangerous than the car or the tractor. And the car is probably more dangerous than the tractor because although there have been no acidents there have been numerous near accidents with the kids in the car and never anything remotely close to an accident on the tractor.
When working with me they learn valuable skills and a good work ethic. My 5 yr old was a huge help when putting in a picket fence. She did all the back filling! And she caried rails (or drug them). I didn't ask her to do this, she would rather work with dad than play. When she was 3 I started teaching her to drive the zero turn and the loader. At 4 she looked like a seasoned pro on the zero turn (she does not mow, that is many, many years away). But once she is mature enough to fully understand and respect the mower, she will not have to learn to use it. She'll already know how.
She has tremedous respect of the machines already, understands what death is and is very cautious. She is not allowed within 50 feet of me when I'm operating any machine. If she wants my attention she has to get into my line of sight from 50+ feet away and wave. She does not approach until I shut the machine down. But then when she gets to me, I teach her, she rides with me and she learns. We do everything very, very slowly. This is valuable time for a father to spend with his kids. Not only do they get father time, but they learn a good work ethic and they learn skills so they wont be helpless like so many adults are today!