Why? Because a big part of them are cheap f***s who either employ illegals for slavewages or simply ship their entire manufacturing and QA operations overseas to places where labor is cheap and they don't have to worry about pesky things like unions and labor protection laws? Should I just do like the rest of you do and blame the illegals for everything? What about the fact that over hear, in the absence of illegals, they're just systematically taking advantage of unemployment internships instead because they're free labor?
As long as you have pricks gleefully taking advantage of this cheap labor they're going to keep coming. Fortify that border all you want, they'll keep smuggling them in by the boatload as long as smuggling in illegals is cheaper than legally hiring employees. Especially since these people never seem to end up in prison where they belong.