Well, the plight of the migrant worker is a theme that constantly gets drummed into the skulls full of mush of young, impressionable 16 & 17 year olds across this country when they read novels such as Of Mice and Men and The Grapes of Wrath. I dunno. Being an English teacher myself, it's just something imbedded in our DNA to do (j/k). This English teacher of "yours" has found an opportunity to slip in either her own personal agenda or one that's been "approved" by the way higher ups. It's not uncommon AT ALL to get a socialist/communist/global agenda in any public high school subject that's on the "soft" side (as opposed to the "hard" subjects like math and science... there's still not a lot of argument among mathematicians about how to factor polynomials).
Whenever, in my teaching experience, I find a position or theme/current of thought that I disagree with, or it doesn't line up with the Word of God (since I'm a Christian), I use it as a teaching opportunity. I state to my children that they will meet many people in life who will support this or that view. What is important (to me) is to know what scripture has to say about a topic, and where there isn't any clear directions, look for Biblical principles or godly character qualities that might apply. That little thought process helps me to define a Biblical worldview, which is where I personally get most of my opinions on things. I have had to change some of my positions on social/political views at times when what I thought in the past was Biblically correct was actually thought manipulation by the ptb. You understand how that goes. :-)
All that to say, you, as Mom, have a unique priviledge to use these types of experiences to train your daughter how to respect others' opinions but THINK FOR HERSELF. Hallelujah! Believe me, when she goes off to college at 18, if y'all decide that's the best thing to do, it only gets worse. She will have plenty of opportunity to state her views both in and out of the classroom when she gets on to a college campus. Praise God you have a daughter who can come to you and tell you what's going on in her life. How many daughters are already "missing" at her age?
So, teach your daughter how to be a "chameleon" in class in order to keep her grades up in school. If she's asked to write a position paper or essay regurgitating the teacher's opinions, she can clear her conscience if she needs to by writing a short disclaimer at the end of her piece. It HAS been done before. lol Then get the A and move on.