You don't start rolling on the background tables until you're 18, it's only the most recent 4 years of your life. If you're a farmer, you've been living on a farm for 18 years, and working on the farm for well over half of that, probably herding sheep or milking cows since the age of 5. My uncle helped with a sow birthing at age 7, his father came and took him out of school to do it because he needed his small hands.
Sure, a more detailed character creation system might be good for some, but too much for others.