Do American farmers mainly work on farms?

Farmers generally don't work or hire employees.

Whether it is an immigrant farm or an American farm such as breeding, planting and hunting, farmers who can afford it generally don't do it themselves. Unless it's those small farms. If China people buy farms and legally employ 10 people with American identity within two years, they can emigrate.

Here is a picture of a California farm:

Xingtiao house purchasing hansi