Realistic, Political
There's no doubt that, with Trifles, Glaspell was channeling the theatre's founding father of realism: Henrik Ibsen. Just like Ibsen, Glaspell has her characters speak like normal people do.
Yeah, it may sound a little stilted to us today, but Midwestern farm folk really used to talk like the characters in the play. When Glaspell's audiences heard Hale say, "How do, Mrs. Wright, it's cold ain't it?" it sounded totally normal to them (20).
Besides the dialogue, Glaspell also puts her characters in realistic situations. Even if murders don't happen every day in the play's rural setting, it's believable that such a murder could happen. It's not as fantastic as, say, aliens coming down and strangling Mr. Wright.
Also like Ibsen, Glaspell used her realistic plays to critique society. Similarly to Ibsen's A Doll's House, Trifles is totally unafraid to say, "Hey, society! Look at the way you're treating women!" The realistic settings and situations made it harder for audiences to say to themselves, "Meh, that's not happening in my backyard."