The TFWers on farms are doing backbreaking work busting their ass all day in a hot field. Good luck finding any Canadian willing to do that sorta work. IIRC there are also certain crops that require specialized labor to harvest correctly. The work is so seasonal you could never maintain a workforce to support that - I believe they bounce around NA/SA for weeks at a time as things come to harvest.It still blows me away there are no temporary farm workers in Canada that qualify for the jobs.
The TFW program does have its flaws but makes sense for certain scenarios. It gets a bad wrap from the farmers forcing people into slum like living conditions. You also have ****** companies like Tim Horton's abusing it because they don't want to pay market value for Canadian workers - e.g. when Alberta was at the peak of their oil boom the average entry level wage was significantly higher than the minimum wage and Tim's feels they are entitled to an endless stream of minimum wage drones.