Well, let's put it this way: These characters aren't going to be hosting Masterpiece Theater any time soon. This is not a stuffy or prim crowd, and it shows in the dialogue.
There are lots of examples, but let's just look at the final lines of the play, where the Old Man insists yet again that he's married to Barbara Mandrell: "Ya' see that picture over there? Ya' see that? Ya' know who that is? That's the woman of my dreams" (584).
As this snippet demonstrates, words are often abbreviated or written more casually to reflect a more loosey-goosey speaking style—so, here, "you" becomes "ya'." There's a lot of "gonna" throughout—that's a big one. From those stylistic flourishes, you get a sense that these people aren't very hoity toity—they're normal folks, and they aren't afraid to tell it like (they think) it is.