As a staunch communist, Brecht is no fan of the capitalist system, which he sees as being built on the exploitation of the working-class or proletariat.
Although capitalism is, as he fully acknowledges, a man-made economic system, it has developed to the stage where it has a relentless momentum all of its own.
That being the case, people all too often find themselves helpless, overwhelmed as they are by the powerful, rapidly-developing forces of capitalism, forces over which they have no control. In The Good Woman of Setzuan, Shen Te finds herself in a similar position. She comes to realize that resisting the forces of capitalism is futile.
Her natural goodness and generosity lead to her business getting into serious trouble. This is because, in capitalism, there is no place for the kindness of the human heart, only the relentless pursuit of profit. Faced with this stark realization, Shen Te needs to change her attitude, to become tougher and more resolute, if she's to survive and thrive in the cutthroat world of capitalist competition.
She does this by adopting the persona of Shui Ta, a fictitious male cousin. Shui Ta understands that in order to avoid feeling helpless in the face of capitalism's sheer remorselessness, he has to get with the program, so to speak, to internalize the values of capitalism and become an exploiter rather than join the mass ranks of the exploited. In a dog-eat-dog world, it pays to be the dog that does the eating.
Before long, Shui Ta's utter ruthlessness has not just saved the business but expanded it. In due course, he becomes the owner of a large factory in which he exploits his employees. They feel helpless in the face of capitalism, but there is little they can do about it. The capitalist system as presented to us by Brecht induces a sense of fatalism and helplessness in the proletariat, a sense that they will always be at the mercy of ruthless capitalists like Shui Ta.