They aren't "undocumented workers". They are here illegally. They do not legally qualify for documents. I went thru the nightmare of getting documents and following the law for my wife and the two kids we adopted. My daughter-in-law has gone thru the legal process required to get documents - but then, they are from the Philippines. Filipinos and Filipinas don't have the 'right' to be "undocumented workers". That is just for Mexicans, or those from central America.
Slavery might have been good for the economy, but that didn't make it right. Paying pee-poor wages and being able to abuse someone because they are afraid of the law isn't moral either. I'm not so desperate to eat fruit that I couldn't pay more to buy fruit picked legally.
I'm also not thrilled with importing Mexican culture. Mexico is politically corrupt, and bringing in millions of Mexicans and not requiring assimilation means our culture becomes more like the corrupt political culture of Mexico. And it also is bringing in crime and violence, because a border that isn't controlled makes it simple to bring in drugs. Many of the areas I hiked in as a kid are now marked with warning signs, because the government makes no attempt to prevent armed drug runners from crossing thru. My son-in-law has come across drug and gun caches while riding a dirt bike. When I go hiking now, I carry at least one gun with me. Often two - one openly, and one concealed.
That is a change that has come about because the border isn't controlled, and it isn't controlled because Democrats want to pander to tribal voting by Hispanics, and the GOP-E wants slave labor for big business.
I see no morality in our current policies. We could easily allow employers to check on citizenship, and then drive out of business those who hire "undocumented workers". We could greatly expand the guest worker program. If that drives up the cost of apples, so be it. We could give ranchers on the border the right to defend themselves. But then, that would require us to be a serious country - one that would vote based on things like deficits or crime instead of tribal loyalties...
BTW - "There has never been a case of an undocumented worker voting illegally."
Given the total lack of enforcement, and how difficult the courts & feds have made it to CHECK on the citizenship of those who vote, how would anyone know?