If those in power were really concerned with illegal immigrants they would pass a law, with teeth, making employers responsible for hiring.
In fact with unemployment being so low we are going to need more, yet Trump has lowered the legal number.
an interesting article, here's a snippet:
There are about 11 million immigrants in the United States who came here illegally. (If you’re curious how we can be fairly certain about that, here.) In total, nearly 45 million residents of the United States were foreign-born. In other words, about three-quarters of immigrants in the country are here legally.
http://www.washingtonpost.com/news/politics/wp/2018/06/28/most-immigrants-are-in-the-u-s-legally-something-most-americans-dont-know/?utm_term=.18b11b4e1528