I agree with the replies that things were greatly different in the ancient history days! We had an old 8N, and a big old McCormick Farmall, I think it was a 1947, or maybe 49, and I think it was an 'A' model? Anyway, it was the big tractor. I used these things way younger than you would be allowed today, someone would accuse you of child abuse now! I was stopped by being small, I would have to stand up to operate the pedals until after I got out of High School.
My brother was a good bit taller than me, and he always ran the tractor. About 1967, he was bush hogging in our upper field, I had just popped in to get a drink of water and saw the tractor swerve like he had gone crazy, JUST before he ran through the fence! Dad saw me running and took off behind me figuring something was wrong. BTW, he would have been about 17 at the time.
We got there, he had enough sense to stop the tractor and saw the basic problem. A fairly sizable black snake had gotten caught up in the PTO and when it was launched, wrapped around his neck! Nearly strangled him in addition to scaring several years growth out of him! Snake was DOA!
Got it unwrapped, and that is, of course, when little brother hits the ground laughing at him! That only lasted for a hot second until Dad told me to go get some lumber and fix the fence......NOW!
Anytime I was having some fun, it seemed to come back and bite me!!
I think it's a great idea that your teaching your children to run the equipment, responsibility never permanently crippled any of us!
George