On the Americans wouldn't do these jobs for minimum wage part of this 1 they don't pay them minimum wage and 2 you'd be surprised what high school kids will do for minimum wage.
You'd be surprised what kids will do for less than minimum wage. Some places such as community pools hire minors to work below minimum wage and can get away with it because it's considered to be a seasonal job. I imagine that the same thing applies to the agricultural industry as well as other industries.