How does Fitzgerald use the characters of Tom and Wilson to criticise American Society in the 1920's?
In The Great Gatsby, Wilson is at the bottom of the social and economic system and Tom is at the top.
One specific story line accurately demonstrates this. Wilson needs to buy Tom's car so he can resell it and earn money. That's one thing Wilson does to earn a living: buy and sell cars. Yet, when, as well as if, this business transaction occurs is completely in the power of the haves (Tom), rather than the have nots (Wilson). The man with the car possesses the power. Apparently, the discussion or negotiation concerning the car has been going on for some time. Wilson needs the deal to happen quickly, but Tom is taking his time. When Wilson asks about the car, Tom gets upset and says that maybe we should just forget the deal, then. Tom has all the leverage. Wilson is at his mercy.
Wilson is the one who works even when he's sick so that he won't miss a sale, but Tom is the one with all the power.
Other aspects of humankind are ridiculed in addition to the social and economic, however. One aspect of humanity that serves as an equalizer in the novel is the foolishness of both Wilson and Tom. In other words, both Wilson and Tom are fools.
Wilson is jerked around by Tom, cuckholded by Tom, fooled by his wife, and, at least in part, suckered into killing Gatsby by Tom.
Tom is as ignorant of Daisy's affair as Wilson is of Myrtle's, he latches on to cliche, tired, irrational arguments concerning race, etc., he rashly judges people and situations based on his own needs and point of view, and he thinks he is always right.
Thus, both public and private aspects of the Jazz Age are ridiculed in the novel.
One shouldn't, of course, however, make the mistake of assuming the novel only applies to the Jazz Age. The novels criticism applies to us and our age as well.
It seems as if there is a statement being made about the nature of men in both characters. They both lack a constructive voice with which social orders are improved. Tom is a insensitive, singular dimension man who is only concerned with satisfying his own desires and needs. The social circle to which he belongs is driven through self interest and this is not only proven in such a setting, but also through his affair with Myrtle. Completely engrossed in his own satisfaction, Tom is a jerk and it is brutal to realize he ends up "winning" in the end. Tom represents that aspect of the Jazz Age society where wealth and privilege were not used to make others' lives better, but rather to indulge one's own inflated sense of self. It is no surprise that the Crash of 1929 ends up plunging a nation into social and economic chaos if people like Tom were the ruling wealthy elite. Tom's success comes on the backs of people like Wilson. He is a low grade mechanic who is frustrated at much in his life. The fact his wife is with another man, the fact that he is powerless to change that or his lot in life, and that there is a rage burdening within him that has no articulation or no productive expression. It is simply there. Wilson is an example of the people who are stepped on and over by the "Jazz Age" elitists such as Tom. In the end, Wilson's action of killing Gatsby is not a statement of power, but rather an impotent action that does not really solve what ails in the heart nor equalizes out the imbalance of social wealth and privilege. In both men, Fitzgerald makes a statement of what misguided direction and action resembles.