The racism is implicit/unstated, but is as clear as day.
Their implicit, underlying premise is that they're all undesirable because they'll all suck the Arizona economy dry, increase blight, crime, and such. They see them all as lazy, brainless wetbacks, useful at best only as gardeners or as farmhands.
If they realized that Mexicans are no different from them, except for their looks, they'd realize that Mexico can give us entrepreneurs, inventors, and other geniuses too. Then maybe they wouldn't be so quick to throw them out.
Perhaps a Mexican in Arizona had received top grades in school, has had the courage to leave his/her home, to travel hundreds of miles, to try and learn a new language and an unfamiliar culture; all in hopes of pursuing a career and to work for a better life for him/herself and family. These assumptions probably never occur to Arizonians.
This form of racism is just one step away from that practiced in Nazi Germany -- where people had to fill questionnaires and submit documents about their ancestry for generations back, in order to prove their "Aryan" descent and/or disprove their Jewish roots.
Oh, well -- welcome to Arizona.