Kids can be surprisingly useful resources at a surprisingly early age.
On farms, as you’ve said, kids can figure out what to do and help out easily. If your work requires a lot of low-skill repetitive manual labor, kids can do that, and it can help teach them how to do your slightly higher-skill labor next year.
This does not apply if you work as an engineer, or in an office, or many other cases where specific skills contingent on mostly-finished-developing brains are required to do your work and there is no manual labor that you can offload to children. If you expect your kid to go through the standard college route, there are 22 years of waiting before they can really do anything useful to help with your labor.
On farms, as you’ve said, kids can figure out what to do and help out easily. If your work requires a lot of low-skill repetitive manual labor, kids can do that, and it can help teach them how to do your slightly higher-skill labor next year.
This does not apply if you work as an engineer, or in an office, or many other cases where specific skills contingent on mostly-finished-developing brains are required to do your work and there is no manual labor that you can offload to children. If you expect your kid to go through the standard college route, there are 22 years of waiting before they can really do anything useful to help with your labor.