The first two are about guns and the after-effects of shootings. Oates' writing is so strong that even when the titles, "Solider" and "Gun Accident," might be considered spoilers, the impact is not reduced. The theme here is the pain and terror of the survivors, two very different shooters with two very different responses. Both are equally horrible.
The final two stories are about victimized women, actually a woman and a girl. Here again, the terror is real and long lasting. The author magnifies the impact with unresolved endings, so the reader is forced to continue to think about the story afterward.
If you haven't read anything by Joyce Carol Oates, you are missing one of the great living authors. This is a good place to start.
When writing about women, the author includes two themes.
The first is the control men exert over women, as a subtle, psychological power.
"Rarely was the wife able to withstand the husband's wishes."The second is the fantasy women have prevents them from acting in their best interests.
"And he was her protector. He would not want anything to happen to her, surely?"While one might wish that these themes were not applicable in the 21st century, these stories are too real and well-written to support that fantasy any more than the dangerous fantasies of the women in the stories.