I don't see anything wrong.
I too grew up in a different time (which was not all that long ago).
Never had any tractors with ROPS, or seat saftey switches, etc. I learned my way around a tractor on an 8n ford. I had to stand up to reach the clutch. If it had a seat switch, I'd wouldn't have got to drive for at least 3 more years.
I always remember riding with dad like that. Standing on the floorboard and sitting on the tool box.
He (dad) is always telling me stories of his chilhood on the farm. Discing the fields all by himself when he was only 8 years old with their old oliver cause it was their only tractor with a hand clutch. Or the times he was riding just like in the pics when grandpa was plowing and falling asleep. Grandpa would hit the clutch (which would stop quick with the plow in the ground) and he would fall right off the tractor.
Everything has risks and some things are just plain stupid. But people were raised differently and come from different backgrounds. What may look dangerous to one, may be common practice to another.