I think that the author believes there are responsibilities between all people, no matter how much money they do or do not have. I also believe that the author was influenced by the communist ideas of Karl Marx, indirectly if not directly.
When the family is looking for work out west, the book talks about how the big farms managed to shut down the little farms and bring in so many workers that they could pay them scandalously little (Steinbeck 237-238). The author says sarcastically that it is a good thing, and later says that the anger the big farmers are causing will be their destruction. It does not really matter if you make people angry, as long as they do not consider it an injustice. However, the workers do see it as an injustice because they think the farmers are responsible for them. For example, workers compare how the farmers treat them to how the farmers would treat one of their horses (Steinbeck 296). They compare themselves to things the farmers own and are responsible for, implying that they think the farmers are responsible for them. But, in my opinion, no one can be responsible for another person. People are only responsible for themselves and their children, should they have them.
I found many of the ideas in the book to be strongly leaning toward communism, just saying. The idea of a collective soul has me really freaked out, especially because it is presented as a noble truth (Steinbeck 22). Communism preaches and raves about the collective and the common good. The characters also wish they could form a union, and unions stand for collective bargaining, yes, another collective. Tom even speculates that he may kill people to start a union (Steinbeck 345). Do I need to point out how wrong that is? Though the author may not know it, but most likely he does, he was certainly influenced by that ideology which kills the individual.
Steinbeck, John. The Grapes of Wrath. New York: Penguin, 2002. Print.