The reason the powers that be are creating an environment that encourages illegal immigration and discourages legal immigration is because the workers can be paid less if they aren't here legally which, of course, puts pressure on people who are here legally to work for less.
One of the reasons there is such a large influx of people wanting to come across the border from the south is because the US is destroying the ability of the small farmers in those countries to make a living by flooding those countries with cheap, subsidized agricultural products.