There's not a farmer in this world that didn't start his or her tractor driving carreer of by riding with dad to learn how to run one. I did, my kids did, my grandson is learning now. But there's a "safer" way. (NO way is totally without risk) I learned with ME sitting in the seat and dad as the rider. He put himself at risk and not his young child. There was a great deal of instruction before the tractor ever moved. Once we started moving, speeds were kept to an absolute minimum, operating on flat, clear ground. As soon as I was ready, dad dismounted and I was "flying solo". We were never allowed to simply "haul passengers" on the tractor itself.
And in no event was there a manure spreader, bush hog, plow,disc, or ANY implement hooked to the tractor while learning, muchless in operation. I was in my middle teens, and very used to operating a tractor SAFELY before I was allowed to operate certain equipment. (Balers, mowers, cornpicker, ect)
Some people are simply an accident looking for someplace to happen.