Class and economics as plot drivers
In social realism, the events of the plot are generated by economic and social forces rather than by individual psychology alone. A character loses their job, which means they cannot pay rent, which means a set of social relationships and possibilities collapses. A character's class position closes certain doors before they reach them. The economic forces that drive the plot should be specific rather than general: not “poverty” as an abstraction but the specific mechanics of a particular economic situation in a particular place and time. The writer who understands how the economic system their characters inhabit actually works, in specific detail, will produce plot events that feel inevitable rather than contrived, because they are generated by genuine structural logic rather than authorial convenience.