It doesn't?
Wow! Seattle would love to hear this!
This is the study from Washington State University. This is the cost per acre for picking lettuce:
Packing:
Packing labor hour $12.00 x 300 hrs = $3,600.00 Packing by hand
Cartons 24 ct carton $2.80 X 813 = $2,275.00
There are 24 heads per box so 813 boxes times 24 = 19,512 heads/acre. The labor per acre is $3,600 so the PER HEAD cost of labor is a whopping $0.19 or 19 cents.
So DOUBLING the labor cost to $24.00/hr makes the per head cost go up 19 cents. When you pay a buck per head it would now cost $1.19. THIS IS NOT DOUBLING THE COST. It is a 19% ONE-TIME increase.
My point is you would have to Double labor rates to attarct Americans.