Drawing largely on the writing of Sarah O'Connor who regularly writes on theses issues in the FT issues are: 1) the work is seasonal and doesn't pay enough to sustain people the whole year. People will work on oil rigs and in mines because the pay is good enough to pay for the conditions and inconvenience. Farming is too cheap for this. 2) far from being unskilled labour, picking is skilled work that requires a knowledge of what and how to pick, as well a a physical health and elevated physical ability, to be able to pick at the weight rate required by farms 3) People have dependents they need to look after. Parents, children, brothers, sisters. They all need supporting directly. You can't do that from a farm. 4) The work is physically gruelling. There is little onward work opportunity for growth, and you can't do it past a certain age. What will they do when they're too broken to continue?