Illegals make vital contributions to the economy. They pay taxes and, generally, avoid coming under the notice of the authorities. They do this because they are fearful of deportation. They are likely to never collect on the FICA tax contributions.
On the other hand...
Some of the men that get through are criminals and, living underground, are very hard to ferret out. They tend to depress the wage-rates in the lower sectors of the economy. I favor living wages for all.
The reason employers love them should be obvious to all. They can be treated like sh!it, prevented from unionizing, get stiffed on payday etc.

Do you suppose anyone will attempt to answer my question concerning the use of illegals in the armed forces?