I know from talking to backpackers doing picking down Stanthorpe way that initially they do not come to Australia to work...they come for a holiday and a good time. They always are short of cash and any offer of work from any source is usually welcome but I'm not sure that they'd want to apply for a Green Card and all that entails, especially as it will cost. I'm talking about European backpackers by the way. It may deter backpackers from visiting us because one of our main attractions is the freedom we offer.
To start with, not everybody has a Smart Phone, and on top of that, it will cost a hell of a lot of money to set up. Why not just do as I suggested earlier, and have every worker join a Union. Much more economical, and faster to implement.
As I also said earlier, this type of thing is the reason Unions came into being in the first place. To protect the Workers !!!