If you remove the reference to Mexicans in your post, I suspect that taking undesirable jobs at low wages, is what most of any of our own immigrant ancestors did at different points of time in our history.
It didn't lead to class warfare.
Sometimes it does, sometimes it does not. America is fortunate that most of its willing immigrants, have come here to become Americans, and capture the dream, and the ethos. I still believe that is the case, Mexicans included, no matter how much some Hispanic politicians try to make it otherwise. France has done a poor job with its immigrants. It is not used to immigrants really. It was and is an insular society, despite the Fracophone hype to the contrary.