That's because you're working on job sites that hire people such as yourself, Israel.
I will give credit where it is due. These guys do work. They work very hard and don’t pitch and moan about it. When I did inspections it was very rare not to find a drywall crew, roofing crew, framing crew, masonry crew that was not all or mostly Hispanic labor. Both legit and undocumented.
The problem is not that they displace other hard workers who can usually find other jobs or a promotion. The problem is that they displace workers who then go on the dole. Or they fill in labor gaps caused by people who could work deciding not to work.
As much as I think there should be penalties for the hiring of illegal immigrants I know the main reason besides wages such crews are hired. It is that bosses really do want people who will work and get the job done.
When you have to speak Spanish as a foreigner to get a job in a kitchen or construction site, you’ll find that only foreigners are hired.