The cynic in me thinks that this is a way for bigger farms to gobble up smaller farms by calling in ice but knowing that they will be able to keep ice from raiding them unless a bigger farm pays to have them raided.
Illegal migration makes it infeasible to invest in technology to automate the work, because any business that wants to invest in automation will be undercut by a less ethical competitor employing illegal, artificially cheap workers. This also makes it hard to attract investment for companies building technology to automate this work, because investors assume that the government will continue to not enforce the law, leading to reduced demand for labor-replacing technology. We won't get significant innovation and investment in this field until the government sends a clear message that they will be consistently enforcing the law going forward.
This assumes that a machine can do the job, but the present owners don't understand it. The article doesn't say "this will force farmers to mechanise more", see?
At what quality? Most frameworks are paid by amount harvested so they bust their asses to pick all that fruit. What’s the motivation for prisoners to do more than the bare minimum? Related question, what will the other inmates do to the inmate who works much harder than everyone else?
I'm sure a nation with such a... shall we say... "colorful" and rich history in prison and slave labor can muster some experts on the matter to answer your questions. Satisfaction guaranteed, or your money back. Et cetera.
They trust that their bigger political clout will let them continue to employee undocumented migrant workers at wages no one else will work for?
They wait for the political climate to change, and then they'll go back to business as usual?
They wait for produce prices to skyrocket/the job market to crater, and then pay minimum wage for the jobs?
Something something, AI/robots?