Here's what happened up here in Canada. In the late 1980's you could pick fruit/veggies/tobacco/etc and earn enough money to put you through a year of university, if you got on a good farm you could earn enough to put you through 2-3 years. This was still the norm in the early 90's, by say '94ish there was a great push of factory farms. And suddenly there were people saying "oh we can't afford to pay these people those wages." And suddenly they loosened the wage rate, and more followed suit. It went from hourly to bushel, and then you started hearing the "but people won't work for what we're paying!" So they relaxed the hiring regs, and allowed the importing of 3rd world labor to do those jobs. And the wages still fell.
If you want to fix the problem, the laws have to be changed. Most governments have no interest in changing the laws on this, and now it's the norm. Now people are seeing this with the abuse of H1B's in the US, and here in Canada with TFW's. The difference between the two is a TFW can be used in any job. The current area we're seeing a flood of people in is with business cleaning run by fly-by-night shops that hire people who are illegally in Canada. But businesses from the CIBC(big bank up here) replacing workers with TFW's, to skilled trades in the oil patch have been hit.